Sex hormone

Sex steroids, also known as gonadal steroids, are steroid hormones that interact with vertebrate androgen or estrogen receptors. Their effects are mediated by slow genomic mechanisms through nuclear receptors as well as by fast nongenomic mechanisms through membrane-associated receptors and signaling cascades. The term sex hormone nearly always is synonymous with sex steroid.

Male sex hormone easily triggered

Surging testosterone?Scientists have proved that even the most seemingly innocent chat with a woman can be enough to send male sex hormones soaring.
A team from the University of Chicago paid students to come into their lab under the pretence of testing their saliva chemistry.
While there, the students got to chat to a young female research assistant.
Saliva tests showed the brief interaction was enough to raise testosterone levels by as much as 30%.
The more a man's hormone level shot up, the more attractive he later admitted to finding the research assistant.
And perhaps more tellingly, the research assistant herself was able to identify those men who found her attractive.
The men who she judged to be doing the most to try to impress her proved to be those who registered the biggest jump in testosterone levels.
However, little or no change was detected in the saliva of students who chatted with other men.
Animal reaction
Testosterone has long been closely linked with the male libido.
The researchers say their work is the first time that hard evidence has been produced in this way.
It is known that the release of testosterone in animals can embolden them, triggering courtship or aggressive behaviour.
The Chicago team believe the same may be true in humans.
However, lead researcher Dr James Roney said it was also possible that the release of the hormone was stimulated by a stress reaction.
Dr Roney told BBC News Online: "The findings are consistent with the existence of brain mechanisms that are specialised for the regulation of courtship behaviour and thus respond to cues from potential mates with coordinated behavioural and hormonal reactions.
"One might call these reactions components of a "mating response" which, if confirmed by future research, could be as basic and significant as, say, the well-known "fight or flight" reaction."
Dr Nick Neave, of the Human Cognitive Neuroscience Unit at Northumbria University, said the study was "very interesting".
"Other researchers have found changes in male hormone levels after watching erotic movies but this seems to be the first that has attempted to assess hormone changes when males meet women on a more 'normal' level."
Dr Benjamin Campbell, an expert in anthropology at Boston University, said it was possible that testosterone made men more bold by suppressing activity in an area of the brain called the amygdala, which controls the stress reaction.
Testosterone levels peak in a man by his early twenties, and then gradually diminish.
Men who are married or in long-term relationships have lower testosterone levels than those still playing the field.
The research is published in the journal Evolution and Human Behavior.

Estrogen and Testosterone Hormones

The differences between female hormones and male hormones may not be as specific as you might think. The definition of a hormone is a chemical substance produced by an endocrine gland that has a specific effect on the activities of other organs in the body. The major female and male hormones can be classified as estrogens or androgens. Both classes of male and female hormones are present in both males and females alike, but in vastly different amounts. Most men produce 6-8 mg of the male hormone testosterone (an androgen) per day, compared to most women who produce 0.5 mg daily. Female hormones, estrogens, are also present in both sexes, but in larger amounts for women.
Estrogens are the sex hormones produced primarily by a female's ovaries that stimulate the growth of a girl's sex organs, as well as her breasts and pubic hair, known as secondary sex characteristics. Estrogens also regulate the functioning of the menstrual cycle.
In the majority of women, ovarian hormones appear not to play a significant role in their sex drive. In one study of women under the age of 40, 90 percent reported experiencing no change in sexual desire or functioning after sex hormone production was shut down because of the removal of both ovaries.
The Importance of EstrogenEstrogens are important in maintaining the condition of the vaginal lining and its elasticity, and in producing vaginal lubrication. They also help preserve the texture and function of a woman's breasts.
In men, estrogens have no known function. An unusually high level, however, may reduce sexual appetite, cause erectile difficulties, produce some breast enlargement, and result in the loss of body hair in some men.
Androgens are sex hormones produced primarily by a male's testes, but are also produced in small amounts by the female's ovaries and the adrenal gland, an organ found in both sexes. Androgens help trigger the development of the testes and penis in the male fetus. They jump start the process of puberty and influence the development of facial, body and pubic hair, deepening of the voice, and muscle development, the male secondary sex characteristics.
After puberty, androgens, specifically testosterone, play a role in the regulation of the sex drive. Large deficiencies of testosterone may cause a drop in sexual desire, and excessive testosterone may heighten sexual interest in both sexes. However, testosterone levels are poorly correlated with sexual interest and drive when they are within the average range. Sex drive is much more likely to be affected by external stimuli (sights, sound, touch) than by variations in sex hormones, except in extreme cases.
Too Little Testosterone in MenIn men, too little testosterone may cause difficulty obtaining or maintaining erections, but it is not clear whether testosterone deficiencies interfere with female sexual functioning apart from reducing desire.
However, there is no evidence whatsoever to suggest that because women have less testosterone than men do, they have lower sexual interest than their male counterparts. Instead, it seems that women detect and react to much smaller amounts of testosterone in their circulation than men do.

Aging, illness and certain cancer treatments can affect our bodies' delicate hormonal balance, causing changes in sexual interest and functioning. Familiar to most are the changes that occur when a woman goes through menopause. Estrogen production drops throughout this process as a woman exits her child-bearing years.
The major sexual impact of decreased estrogen is a shrinking of the vagina and thinning of the vaginal walls, along with a loss of elasticity and decreased vaginal lubrication during sexual arousal. Some women experience only slight changes in sexual functioning, while others have dryness and pain with intercourse, or genital soreness for a few days after sexual activity, if they don't use a vaginal lubricant or take some form of hormone replacement.
Researchers investigating the effects of hormone replacement therapy on women's sexual functioning have shown that taking estrogen often allows sexual functioning to return to normal. In addition, androgens have been prescribed for postmenopausal women to enhance their sexual desire.
Hormone-Replacement TherapyPerhaps less well known is the fact that men sometimes experience lowered testosterone levels, which can be responsible for sexual dysfunction. How this hormonal decrease affects the man's sex drive and erections remains unclear. But urologists, as a treatment for these difficulties, sometimes recommend testosterone replacement. There is a great deal yet to be learned about which men and women may require and benefit from hormone-replacement therapy.
It is tempting to try to understand sexual behavior solely in terms of hormones. In many animal species hormones that control the female's willingness to mate and the courtship and sexual behavior of the male tightly regulate patterns of sexual behavior.
In humans, however, there is a more complicated relationship between hormones and sexual behavior. Although a substantial testosterone deficiency usually reduces sexual interest in men and women, there are cases in which that effect is not seen.
Similarly, although many men with below normal testosterone levels have difficulty with erections, not all do. Women who have low amounts of estrogen in their bodies do not lose their ability to be sexually aroused or to have orgasms.
In short, sex hormones are not the only factors affecting sexual interest or behavior. If you are concerned about your hormone levels and whether they may be effecting your general health or your sexual functioning, consult your doctor for some easily performed and (almost) painless laboratory blood work.

Sex: The science of sexual

Psychologists are gaining new insights into sexual arousal with the help of innovative research methods.
Men and women experience sexual arousal very differently, not only physiologically but psychologically, according to researchers who are studying arousal using an array of new and refined methods.

Those methods are making it possible for researchers to understand the causes of real-world problems, such as sexual dysfunction and high-risk sexual behavior (see pages 54 and 58). But they are also giving researchers the means to explore basic questions about the nature of sexual arousal and how its different components--such as physiological arousal and subjective experience--are related to each other.

"It's easier to get funding for research that focuses on, let's say, AIDS-related sexual behaviors, than for research on the very fundamental question of what sexual motivation and sexual arousal really are," says Erick Janssen, PhD, a psychologist at the Kinsey Institute for Research in Sex, Gender and Reproduction at Indiana University. "But in the long run, those basic questions have to be answered before we can move on to explain other, related behaviors."

Cognition and arousal

One active area of research concerns cognitive factors that influence sexual arousal. In the mid-1980s, Boston University psychologist David Barlow, PhD, and his colleagues conducted a series of studies to examine the relationship between anxiety and sexual arousal. They found that men with and without sexual problems reacted very differently to anxiety-inducing threats of mild electric shock.

Men who reported having no trouble getting and maintaining erections, says Barlow, "would believe that they were going to get shocked if they didn't get aroused, so they would focus on the erotic scene." The result was that the threat of shock actually increased sexual arousal. But men who had sexual problems responded to the threat of shock very differently, says Barlow. "Their attention would be so focused on the negative outcomes that they wouldn't be able to process the erotic cues," he explains.

Since those initial studies, Barlow and his collaborators have been trying to tease apart the factors that distinguish men with and without sexual problems. One of the key differences, he says, is that men with sexual arousal problems tend to be less aware of how aroused they are.

Another difference has to do with how men react to instances when they can't become aroused, says Barlow. "Males who are able to get aroused fairly easily seem unfazed by occasions where they can't get aroused," he notes. "They tend to attribute it to benign external events--it was something they ate, or they're not getting enough sleep--not as characteristics of themselves." In contrast, men with arousal problems tend to do just the opposite, thinking of every instance of difficulty as a sign of a long-term internal problem, either physiological or psychological, he says.

At the Kinsey Institute, Janssen and John Bancroft, MD, the institute's director, have been developing a theoretical model and a set of measurement tools that define sexual arousal as the product of excitatory and inhibitory tendencies. Last year, they published papers in the Journal of Sex Research (Vol. 39, No. 2) describing the Sexual Inhibition and Sexual Excitation Scale--a new questionnaire that measures individual differences in the tendency to become sexually inhibited and excited.

Early research on the model suggests that while a single factor accounts for all of the variation among men in their tendency to become sexually excited (SES), there are two inhibitory factors--one that represents inhibition due to the threat of performance failure (SIS1) and one that represents inhibition due to the threat of such performance consequences as an unwanted pregnancy or a sexually transmitted disease (SIS2).

One implication is that people with different levels of SES, SIS1 and SIS2 will respond differently to different kinds of stimuli, says Janssen. In one study, for instance, Janssen, Bancroft and their collaborators found that people who scored highly on SIS2 were less likely to be aroused by erotic films that included threatening stimuli than people with low SIS2 scores.

"We believe that people who are high in inhibition-proneness are more vulnerable to developing sexual problems, whereas those who are low are more likely to engage in high-risk sexual behavior," says Janssen.

Physiological and subjective arousal

For most of the history of research on sexual arousal, studies involving women have been much rarer than studies involving men. Recently, however, the gap has started to narrow due to the work of psychologists such as Cindy Meston, PhD, of the University of Texas at Austin, Julia Heiman, PhD, of the University of Washington, and Ellen Laan, PhD, of the University of Amsterdam. Janssen and his colleagues at the Kinsey Institute have also begun studying female arousal.

One of the most interesting results to come out of that work, researchers say, is that there are significant differences between men and women in the relationship between physiological and subjective arousal.

"What we find in research in males is there's a very high correlation between their erectile response and how aroused they say they are," says Meston. "But in women we get low, if any correlations."

In addition to being interesting from a scientific standpoint, the sex difference could also have important implications for the treatment of female sexual dysfunction, says Meston. Researchers have not yet been able to pinpoint the source of the difference, she says, but some progress has been made.

Several explanations that once seemed likely candidates have been eliminated in recent years. One of them is the idea that women are less likely than men to talk honestly about their sexuality because of sexual taboos. But Meston says she sees no evidence of reticence in the women who volunteer for her studies.

Another possibility is that erotic films might evoke negative emotions in women, which could mask their arousal. But Laan and her collaborators at the University of Amsterdam have found no evidence that such reactions can account for the physiology-experience gap.

Meston and others suspect that the difference probably has something to do with the fact that male genital arousal is simply easier to notice than female genital arousal. Men also seem to be more attentive than women to all kinds of physiological signals, not just sexual ones, says Janssen.

An open question is whether the resulting sex differences in the relationship between physiological and subjective arousal are permanent, or whether they can be changed through training. Meston says her lab is currently conducting a study to find that out.