Oxytocin, a hormone best known for cementing the bond between a mother and her newborn child could also play a part in selecting a partner.

Other research along this line has hinted at the importance of Oxytocin in certain social situations between adults. For example, people administered with the hormone made overly generous offers in an economic game that measured trust; whilst men who got a dose of Oxytocin proved better at remembering the faces of strangers a day later, compared to subjects who received a placebo.

According to this new study, published in the journal Hormones and Behavior, researchers found that men and women who inhaled a spritz of the hormone rated strangers as more attractive.

Angeliki Theodoridou, a Psychologist at the University of Bristol, who led the study said:

[When Oxytocin courses through our blood,] we are more likely to see people we don’t know in a more positive light

This effect adds to the hormone’s known role in human relationships.

The researchers tested 96 volunteers in a double-blind, placebo-controlled trial, where participants received either a spray of Oxytocin or a placebo. Subjects were then asked to rate pictures of 48 men and women for attractiveness, and 30 for trustworthiness. The team also tested for mood.

The results showed that subjects who received Oxytocin tended to rate both male and female strangers as both more attractive and more trustworthy – regardless of their mood.

The research didn’t examine how Oxytocin could affect social judgements, but Theodoridou speculates that the hormone dampens brain activity in a region involved in processing fearful emotions, called the Amygdala – A previous study had found that Oxytocin tempered Amygdala activation in volunteers who saw a face that had previously been paired with a slight shock.

Although Theodoridou’s study shows that Oxytocin acts similarly on both men and women when rating strangers, sex differences could emerge in real-world situations, noted Jennifer Bartz, a Psychologist at Mount Sinai Medical School in New York. More research is needed to see if this is the case, she said.

Regardless of Oxytocin’s social effects, greedy entrepreneurs have already been trying to cash in. One company already touts a spray that claims to engender trust in others, although it offers little more than testimonials as proof for its efficacy.

Could a similar spray spark romances between total strangers? Theodoridou doesn’t think so. “I would not endorse any of these products,” she stated.

Posted by Jonathan as Biochemistry, Psychology at 2:27 AM BST

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Currently, the most practical ways to stop HIV transmission are protected sex, monogamy (with an uninfected partner) or abstaining from sex altogether. However, researchers have spent many years without success trying to develop another option – a gel that women (and possibly men) could use to kill the virus before it enters the body.

Whilst condoms can block the virus, many women who want to get pregnant won’t use them, and so they risk infection from their partners. However, now it seems that a new sexual gel might curb the spread of AIDS by stopping cells vulnerable to the virus from rushing to the site of infection.

Previously, researchers have had difficulties destroying the virus without harming the person in the process; and some gels have actually made virus transmission easier by causing tears in the lining of the vagina.

Now, according to a study appearing in the journal Nature, Scientists have reported that a common germ-killing compound has prevented transmission of SIV (an HIV-like virus found in monkeys) – which is an encouraging sign that it could also work in humans.

Dr. Ashley Haase and colleagues at the University of Minnesota in Minneapolis, USA, discovered that a few epithelial cells on the cervix of female macaques are the first point of entry for SIV. After which, nearby immune cells respond by releasing molecules that trigger inflammation and summon T-cells to the cervix.

Under normal circumstances, those T-cells would destroy invaders. However, T-cells are the very same cells that SIV (and also HIV) use to infect their new host.

Using information from studies of Toxic shock syndrome (a life-threatening bacterial infection that can affect women using tampons), chemicals have already been identified that can suppress vaginal inflammation. Therefore, Haase’s team examined a compound called Glycerol Monolaurate (GML), which is already recognized as safe for humans, since it’s a commonly found constituent of vegetable oils, various foods and deodorants – where it kills a variety of germs in addition to helping substances mix properly.

Haase and colleagues tested GML added to a sexual lubricant on five female rhesus macaques that were vaginally exposed to SIV. As a result, they found that four out of five monkeys treated with the gel avoided infection after repeated exposure to the virus, whilst five different monkeys in a control group that only received the lubricant without GML all became infected with SIV, after being exposed to it.

The research seems promising, but there are other important questions to be answered, including whether this treatment would protect men from infection when they have sex with other women (or men), and in any case more experiments in animals will be needed before GML can be tested on humans.

However, the next steps would be to move on to studies that would confirm the compound actually works, and to solve issues such as whether GML would block HIV in a woman’s cervix already inflamed by other infections, or whether blocking cervical immune responses could leave her less protected from other infections.

The surprising good news is that GML could eventually make its way into sexual lubricants that women could use, and would cost less than a cent per dose for each woman.

Thus, the researchers argue, even if the compound were only 60 percent effective, it would prevent nearly a million HIV infections a year, and might slow the spread of AIDS.

Posted by Jonathan as Biochemistry, Biology at 2:23 AM BST

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Forget sugar and spice and all things nice, women smell of Onions and men smell of Cheese – or at least their armpits do – according to Scientists at Firmenich, a company in Switzerland that researches flavours and smells for the food and perfume industry.

The researchers took armpit sweat samples from 24 men and 25 women after they had spent time in a sauna or ridden an exercise bike for 15 minutes.

Then, after the samples had been analysed, the team found that those from women contained ten times as much of an odourless sulphur-containing compound, which when mixed with bacteria commonly found in the armpit, was transformed into a thiol – a previously discovered odour from armpits that is similar to onion.

The sweat of men was different, since it had relatively high levels of an odourless fatty acid which turned into a cheesy odour when exposed to the same types of bacteria.

Christian Starkenmann, whose team’s results appear in Chemical Senses said:

Men smell of cheese, and women of grapefruit or onion.

Bacterial enzymes turn the otherwise odourless precursor into the malodour. Then, the balance of “oniony” to “cheesy” precursors in women’s sweat made it smell worse than men’s as rated by independent smell assessors.

The team now believe that their research could lead to the development of new ingredients for deodorants that are aimed specifically at men or women.

Starkenmann said:

We could make inhibitors that neutralise the precursors, or block the bacterial enzymes that do the conversion.

But, some scientists are sceptical that gender is the deciding factor, and point out that outside of Switzerland people have different diets and genetic backgrounds.

Professor Tim Jacob, who researches the science of smell at Cardiff University, told New Scientist magazine:

Other factors include what you eat, what you wash with, what you wear and what genes you inherit.

Posted by Jonathan as Biochemistry at 2:04 AM BST

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Women with high levels of the sex hormone Oestradiol (a form of Oestrogen linked to female fertility and reproductive health) tend to consider themselves more attractive and are often found to be more attractive than women with lower amounts of the sex hormone.

According to Doctoral candidate Kristina Durante and Assistant Professor of Psychology Norm Li, young women who produce naturally high levels of Oestradiol are more likely to have affairs, and to change partners more frequently. They also see themselves as more attractive than other women.

The researchers, from the University of Texas at Austin, suggested that those women engage in “opportunistic serial monogamy” i.e. they are open to flings and moving on to new relationships, if a higher-quality mate becomes available.

Kristina Durante explained:

Physically attractive women receive more male attention and, when in relationships, are more likely to be the targets of mate poaching. Attractive women also have especially high mating standards.

Because it’s difficult to obtain a partner who is a good provider and also has good genes, women often have to trade off between having a long-term mate who provides continual material resources and more physically attractive, short-term sexual partners with good genetic resources.

However, highly attractive women demand greater amounts of both types of resources in a male partner, in addition to good parenting and partner skills. Thus, physically attractive women may not only have more alternatives but also high standards that are difficult to satisfy.

Accordingly, they may have fewer reasons to be committed to any particular partner if higher quality potential mates are available.

Previous research has indicated that Oestradiol, which is similar to Testosterone in men, fuels a lust for power in single women – Although Oestradiol levels rise and fall across a woman’s ovulatory cycle – generally corresponding to fertility and interest in sex.

In their study, Durante and Li investigated the relationship between Oestradiol and sexual motivation, by taking saliva samples from fifty-two normally cycling female undergraduates aged 17 to 30, at two points of their menstrual cycle, in order to establish baseline levels of the hormone, and rule out the effect of monthly fluctuations. They then asked the participants to answer a survey about their sexual history and their propensity to cheat on a partner by flirting, kissing, dating, having sex, or maintaining a serious affair.

Participants were also asked to rate their own physical attractiveness, and an independent panel of two male and seven female observers, unaware of the nature of the research, were used as independent confirmation, to score the subjects physical attractiveness from full-body photos.

The researchers found that a woman’s Oestradiol level was positively associated with self-perceived physical attractiveness, but negatively associated with their satisfaction with their primary partner. Women with a higher Oestradiol level also reported a greater likelihood of flirting, kissing and having a serious affair with someone other than their primary partner. But, they were only marginally more likely to date another man.

However, whilst high-Oestradiol women had significantly more long-term relationships, the hormone was not related to the likelihood of having more one-night stands. Durante stated:

Our findings show that highly fertile women are not easily satisfied by their long-term partners and are motivated to seek out more desirable partners. However, that doesn’t mean they’re more likely to engage in casual sex. Instead, they adopt a strategy of serial monogamy.

Kristina Durante theorized that the behaviour could be an adaptation to the high costs of giving birth, evolved from when women were more dependent on men to support them through childbirth and child-rearing, claiming:

For women it’s all about the resources that we need. If you’re going to be getting knocked up there’s a significant cost

The study “Oestradiol Level and Opportunistic Mating in Women” was published in the Proceedings of the Royal Society of London journal Biology Letters.

Posted by Jonathan as Biochemistry, Sociobiology at 2:39 AM BST

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Love is a many splendoured thing; it influences most of our music and art, and Poets would even have us believe that it is beyond comprehension. Although Evolutionary scientists would no doubt be keen to point out that Love has evolved to help keep pairs bonded together.

As to the question of what is Love? Neuroscientist Larry Young believes that he may have the answer. Writing in a paper published in the scientific journal Nature, Professor Young argues that Love is a series of neurochemical events in specific brain areas, and has a “biological basis that we can understand”.

Professor Young, of Emory University in Atlanta, Georgia, USA, analyzed the responses of North American Prairie Voles (which, unlike most other animals, form lifelong pairs and raise their young together) to various chemicals, and found that a dose of the right hormone could drastically alter their relationships.

Oxytocin is one of the main hormones involved in generating feelings of love, especially in females. But, Prairie voles artificially injected with large quantities of Oxytocin were found to be very likely to become strongly attached to the first male they encountered – whereas, in the case of males, larger amounts of Vasopressin triggered bonding and nesting effects.

Extrapolating the results obtained with Voles to Humans, Professor Young believes that using this knowledge, a theoretical love potion could be manufactured, which would make the consumer fall in love with the first person that he or she encountered. All that the “cocktail” would do, says Young, would be to trigger a “biochemical chain of events” that would ensure that whoever drank it was convinced that the other person was the right one for him or her. Conversely, an anti-love vaccine could also be invented as an antidote to unrequited love, by reversing the principles that lead to the creation of the love drug in the first place.

Professor Young noted:

If we give an Oxytocin blocker to female voles, they become like 95 percent of other mammal species. They will not bond no matter how many times they mate with a male or how hard he tries to bond. They mate, it feels really good and they move on if another male comes along. If love is similarly Biochemically based, you should in theory be able to suppress it in a similar way.

These experiments have not been conducted on humans, and Professor Young does not advocate that they should be, although he does note:

It would be completely unethical to give the drug to someone else, but if you’re in a marriage and want to maintain that relationship, you might take a little booster shot yourself every now and then. Even now it’s not such a far-out possibility that you could use drugs in conjunction with marital therapy.

However, Professor Young claims that his ultimate goal is not to create a love drug, but to shed light on serious conditions like Autism – by studying brain chemicals involved in emotional attachment. Thus, a milder form of the theoretical love substance might be used to endow Schizophrenics and Autistics with more social skills, in order to help them better integrate into society, and help stop them becoming a burden for others.

Finally, regarding love, Professor Young is convinced that love does not simply boil down to one single hormone. There have been studies where it has been shown that differences in a cluster of genes known as the Major Histocompatibility Complex may be involved in initial sexual attraction, Young pointed out. Adding that variations in this gene cluster have predicted the quality of the relationship between the male vole and its partner.

Posted by Jonathan as Biochemistry, Biology at 10:47 PM BST

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Scientists have long known that animals use scent to communicate. And now, a new study by Psychologists finds that women’s brains recognize and encode the smell of male sexual sweat

The new study, out of Rice University, and published in the Journal of Neuroscience found that socioemotional meanings, including sexual ones, are conveyed in human sweat.

Denise Chen, Assistant Professor of Psychology at Rice, looked at how the brains of female volunteers processed and encoded the smell of sexual sweat from men. So, this study represents an effort to expand knowledge about how human’s sense of smell complements their more powerful senses of sight and hearing.

Chen and her colleagues asked 20 heterosexual males to stop wearing deodorant and other scented products for a few days. Then, they asked the men to put small pads under their armpits whilst they watched pornographic videos and became sexually aroused. They also gathered samples of sweat that was produced when they weren’t aroused.

In the main body of the experiment, the researchers directly studied responses to the human sexual sweat under functional Magnetic Resonance Imaging (fMRI). Using nineteen healthy female volunteers, who inhaled olfactory stimuli from four different sources, one of which was the sweat gathered from sexually aroused males.

The results of the experiment indicated that the brain recognizes chemosensory communication, including human sexual sweat. And also, that several parts of the brain are involved in processing the emotional value of the olfactory information. These include the right Fusiform region, the right Orbitofrontal cortex and the right Hypothalamus.

Professor Chen Said:

With the exception of the Hypothalamus, neither the Orbitofrontal cortex nor the Fusiform region is considered to be associated with sexual motivation and behavior. Our results imply that the chemosensory information from natural human sexual sweat is encoded more holistically in the brain rather than specifically for its sexual quality.

Humans are evolved to respond to salient socioemotional information, and distinctive neural mechanisms underlie the processing of emotions in facial and vocal expressions. So, the findings help explain the neural mechanism for human social chemosignals.

The understanding of human smell at the neural level is still at an early stage. Thus, the present work is the first fMRI study of human social chemosignals.

Posted by Jonathan as Biochemistry, Psychology at 5:55 PM BST

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They say that love is blind, and now, new research shows that it also seems to make things smell differently too.

According to Johan Lundström and Marilyn Jones-Gotman of McGill University in Montreal, Canada, women who are madly in love have difficulty recognising the body odours of male friends, but their ability to distinguish their partner’s smell is unaffected.

The researchers asked twenty young women with boyfriends to fill in a Passionate Love Scale questionnaire, in order to rate how deeply in love they were. They also persuaded the women’s partners and friends of both sexes to sleep for seven nights in a cotton T-shirt with pads sewn into the underarms, to soak up their sweat.

Each woman was then asked to select lover’s or a friend’s T-shirt from three garments, two of which had been worn by strangers. The more deeply in love a woman was, the less well she did at distinguishing a male friend’s odour from those of strangers.

The results showed that the women’s scores on the Passionate Love Scale made no difference to their ability to recognise a lover’s shirt, or even one worn by a female friend. However, those who were more deeply in love were worse at distinguishing a male friend’s odour from those of strangers.

This suggests a lover doesn’t necessarily pay more attention to her partner, and supports a theory of romantic attraction known as “Deflection“, which argues that being in love with someone involves a reduction in the amount of attention given to other potential suitors.

Lundström, now at the Monell Chemical Senses Center in Philadelphia, Pennsylvania, admits that he isn’t a love guru, noting:

The main focus of the project is to look at how the brain processes odours.

He next plans to investigate what happens in lovers’ brains as they perceive the odours of their partners, friends and strangers.

Posted by Jonathan as Biochemistry, Biology at 7:43 PM BST

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In 1956, Denham Harman proposed the theory of ‘oxidative stress‘; in which he claimed that ageing is caused by a build-up of molecular damage to cells, from the actions of reactive forms of oxygen such as superoxide.

These free radicals (oxygen molecules with an imbalance of protons to electrons) are created as by-products of cells metabolising sugars to release energy – So, the Diet and Beauty industry claims that Antioxidants such as vitamins C and E supposedly work to mop these up, thus minimising potential cell damage.

The oxidative stress theory has dominated the field of ageing research ever since it was proposed, but now, a recent study published in the journal Genes and Development, suggests that the idea is probably incorrect and that superoxide is not a major cause of ageing.

David Gems, of University College London, and colleagues at the Institute of Healthy Ageing studied the action of key genes involved in removing superoxide from the bodies of the nematode worm Caenorhabditis elegans, a commonly used organism in research into ageing. By manipulating the worm’s genes, they were able to control the nematode’s ability to ‘mop up’ surplus superoxide and limit potential damage caused by free radicals. This modification should have given the GM nematodes an advantage over normal nematodes, in terms of ageing and lifespan.

However, contrary to the results predicted by the free radical theory of ageing, the researchers found that the lifespan of the worms was relatively unaffected by their ability to tackle the surplus superoxide. So, these findings, combined with similar recent findings from the University of Texas, using mice, suggest that the oxidative stress theory is incorrect.

Dr Gems, who led the study, noted that molecular damage was probably caused by numerous different chemicals within the cell, and went on to say:

Our results spectacularly failed to support the view of the free radical theory.

The fact is that we don’t understand much about the fundamental mechanisms of ageing – the free radical theory has filled a knowledge vacuum for over 50 years now, but it doesn’t stand up to the evidence.

A healthy, balanced diet is very important for reducing the risk of developing many diseases associated with old age, such as cancer, diabetes and osteoporosis, but there is no clear evidence that dietary antioxidants can slow or prevent ageing. There is even less evidence to support the claims of most anti-ageing products.

Dr Alan Schafer, Head of Molecular and Physiological Sciences at the Wellcome Trust, who funded the research, said:

With increasing lifespan comes greater exposure and vulnerability to the ageing process. Research such as this points to how much we have to learn about ageing and the importance of understanding the mechanisms behind this process.

This new study will encourage researchers to explore new avenues in ageing research.

Posted by Jonathan as Biochemistry, Biology at 11:00 PM BST

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Couples who spend more time getting intimate and finding ways to get close everyday may have lower levels of stress hormones in their bodies, a new study suggests.

The findings, reported in the journal Psychosomatic Medicine, indicate that intimacy improves psychological health, but couples need to have a close relationship, or be happily marriage, to benefit.

Researchers from the University of Zurich, Switzerland, studied 51 working, mostly married, German couples for a period of one week, and found that those who reported more physical contact during any given day, whether it was sexual intercourse or just holding hands, generally had lower levels of the “stress” hormone Cortisol.

This was especially true of couples who reported more problems at work, suggesting that some physical affection between mates may be a buffer against work stress.

Many prior studies have suggested that chronic stress may have widespread effects in the body, from dampening the immune system response to contributing to heart disease. Meanwhile, other research has found that married people (at least those happily married) tend to be in better health and live longer lives.

According to Dr. Beate Ditzen, the study’s lead researcher:

It’s possible that the reduced stress response seen with physical affection helps to explain that link

Study participants kept detailed records of their daily activities, including instances of physical affection with their partner, and collected daily saliva samples so that the researchers could measure the fluctuations in Cortisol levels. The couples also recorded their mood at various points of each day, as Good, Relaxed, Alert, Bad, Tired or Fidgety.

In general, the researchers found, the more physical affection couples reported in a given day, the lower their Cortisol levels.

Importantly, Ditzen noted, intimacy was thought to improve hormone levels simply by boosting mood.

But, she stressed, that couples should not race to “express more intimacy, per se,” but rather find things to do together that create positive feelings for both partners.

For couples who do want to become physically intimacy, there are a range of ways to do it, according to Ditzen. She pointed out that “intimacy” meant different things to different couples in the study; to some it was sex, and to others, it was an affectionate touch:

This means that there is no specific behaviour that couples should show in everyday life, rather, all kinds of behaviour which couples themselves would consider intimate… might be beneficial.

Posted by Jonathan as Biochemistry, Sociology at 1:55 AM BST

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According to new research from Utrecht University, the rapidity of ejaculation in men is genetically determined.

Neuropsychiatrist, Dr Marcel Waldinger and Pharmacological Researcher Paddy Janssen studied 89 Dutch men who suffer from the primary form of premature ejaculation, in other words, men who always had this problem.

In their experiment, the female partners of the participants in the study used a stopwatch at home to measure the time until ejaculation, each time they had intercourse, over the course of a month. A control group of 92 men was also studied, and the results will be published in the Journal of Sexual Medicine.

Dr Waldinger emphasises:

This study applies to men who have always ejaculated prematurely from their first sexual contact onwards and not for men who started suffering from this later on in life.

Serotonin deficiency.

In men who suffer from premature ejaculation, the substance serotonin appears to be less active between the nerves in the section of the brain that controls the ejaculation. Amongst other things, this substance is linked to sexual activity and appetite. It’s a substance that transfers a signal from one neuron to another. Due to the low activity of serotonin, this signal transfer does not occur properly in men with the primary form of premature ejaculation.

Gene responsible.

A gene which had already been discovered, namely 5-HTTLPR, appears to be responsible for the amount and activity of serotonin, which means that it controls the rapidity of ejaculation. Three types of the gene exist: LL, SL and SS. The study showed that the LL type causes a more rapid ejaculation. On average, men with LL ejaculate twice as quickly as men with SS, and also almost twice as quickly as men with SL. The researchers are currently also looking for other genes that are involved in ejaculation.

Not psychological.

As far back as 1998, researcher Marcel Waldinger predicted that both the rapidity with which men ejaculate and the primary form of premature ejaculation were genetically determined, explaining:

This theory contradicts the idea, which has been common for years, that the primary form of premature ejaculation is a psychological disorder. The results of our research confirm the genetic theory and may contribute to possible gene therapy against premature ejaculation.

Posted by Jonathan as Biochemistry, Biology at 3:36 AM BST

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