The endocrinology of sexual arousal

May combine two claims. The quote only partly states this claim.

In women who had undergone surgical menopause 1-10 years previously, all with impaired sexual function and on Premarin, there was a substantial placebo response; however, there was significantly more improvement with the higher testosterone dose than with placebo on measures of frequency of sexual activity, and pleasure/orgasm, though not for sexual desire or arousal.

“There was a substantial placebo response; however, there was significantly more improvement with the higher testosterone dose than with placebo on measures of frequency of sexual activity, and pleasure/orgasm, though not for sexual desire or arousal (the opposite pattern reported by Sherwin et al. 1985).”

• cites Shifren et al. (2000) sourceSupported

May combine two claims.

The locus coeruleus has testosterone receptors, and the putative 'excitatory tone' can be regarded as testosterone dependent.

“The l.c. has testosterone receptors (Parmeggiana & Morrison 1990), and this putative 'excitatory tone' can be regarded as testosterone dependent.”

• cites Parmeggiana & Morrison 1990Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Without testosterone, the erectile response is 'stimulus bound', receding as soon as the stimulus is switched off; with testosterone replacement, the response shows greater rigidity and lasts beyond the sexual stimulus.

“Without testosterone, the erectile response was 'stimulus bound', i.e. would recede as soon as the stimulus was switched off.With testosterone replacement, the response would not only show greater rigidity, but would also last beyond the sexual stimulus (Carani et al. 1995).”

• cites Carani et al. 1995 sourceNot checked — no full text of the source

May combine two claims.

Age-related changes that may be relevant in older men include altered negative feedback of testosterone and hence less increase in luteinizing hormone with falling testosterone levels, increased sex hormone binding globulin and hence relatively reduced free testosterone, and the likelihood of an age-related decline in testosterone receptor sensitivity.

“A number of age-related changes may be relevant: altered negative feedback of testosterone and hence less increase in luteinizing hormone (LH) with falling testosterone levels, increased sex hormone binding globulin (SHBG) and hence relatively reduced free testosterone and the likelihood of an agerelated decline in testosterone receptor sensitivity.”

May combine two claims.

In eugonadal men, increasing testosterone has no effect on frequency of sexual activity or daily measures of sexual interest.

“Bagatell et al. (1994b) and Yates et al. (1999), in eugonadal men, found no effects of increasing testosterone on frequency of sexual activity, or in the latter study, daily measures of sexual interest.”

• cites Bagatell et al. (1994b)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Yates et al. (1999) sourceNot checked — no full text of the source

May combine two claims.

Effects of testosterone on sexual activity with a partner are less consistent, partly because they depend on partner and relationship characteristics.

“Effects on sexual activity with a partner are less consistent, partly because they depend on partner and relationship characteristics.”

May combine two claims.

Varying testosterone levels within the normal range produces no difference in sexual activity, sexual interest or NPT, although rigidity of NPT was not measured.

“They found no difference in sexual activity, sexual interest or NPT, although the rigidity of NPT was not measured.”

• cites Buena et al. (1993) sourceNot checked — no full text of the source

May combine two claims.

In male studies of testosterone withdrawal and replacement, placebo has only a modest effect, but testosterone replacement restores sexual interest and arousability.

“Typically, in male studies of this kind, placebo has only a modest effect, but testosterone replacement restores sexual interest and arousability.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Whereas the traditional concept of 'hormone' continues to apply to the role of testosterone and oestradiol in sexual arousal, peptides present a more complex role.

“Whereas the traditional concept of 'hormone' continues to apply to the role of testosterone and oestradiol in sexual arousal, peptides present a more complex role.”

May combine two claims.

Nocturnal penile tumescence is clearly impaired in hypogonadal men and restored to normal with testosterone replacement.

“NPT is clearly impaired in hypogonadal men, and restored to normal with testosterone replacement.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The role of peptides in sexual arousal remains uncertain, partly because of the multiple roles and sites of action of most peptides.

“The role of peptides in sexual arousal remains uncertain, partly because of the multiple roles and sites of action of most peptides.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

The relevance of aromatization and of non-sexual effects of testosterone that might indirectly influence sexual arousal is not well understood.

“The relevance of aromatization and of non-sexual effects of testosterone which might indirectly influence sexual arousal are not well understood.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The extent to which testosterone in women acts by conversion to oestradiol or by increase of free oestradiol is not yet clear.

“The extent to which testosterone in women acts by conversion to oestradiol or by increase of free oestradiol is not yet clear.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

If testosterone withdrawal lasts long enough, seminal emission will eventually be impaired.

“If testosterone withdrawal lasts long enough, seminal emission will eventually be impaired.”

Probably not a substantial claim: may not pass S4 (based).

One possible explanation for the more complex, less consistent picture of testosterone in the female is greater variability across women in responsiveness to testosterone.

“One possible explanation is a much greater variability across women in responsiveness to testosterone.”

May combine two claims.

In a cross-sectional study of teenage boys, the free testosterone index was a strong predictor of 'sexual motivation', whereas stage of pubertal development was not predictive.

“In the first (Udry et al. 1985), a cross-sectional study, the free testosterone index was found to be a strong predictor of 'sexual motivation', whereas stage of pubertal development was not predictive.”

• cites Udry et al. 1985 sourceNot checked — no full text of the source

May combine two claims.

In eugonadal men, weekly injections of testosterone enanthate (200 mg) over 8 weeks had no effect on sexual activity, either with a partner or as masturbation, but significantly increased a measure of sexual interest independent of sexual interaction with the partner.

“Anderson et al. (1992), using weekly injections of either placebo or testosterone enanthate (200 mg) over 8 weeks, found no effect of the exogenous testosterone on sexual activity, either with a partner or as masturbation, but a significant increase in a measure of sexual interest independent of sexual interaction with the partner.”

• cites Anderson et al. (1992) sourceNot checked — no full text of the source

May combine two claims.

The roles of testosterone in the development of sexual arousability and in the aging male are less clear.

“The roles of testosterone in the development of sexual arousability, and in the aging male, are less clear.”

Classified as probably not a substantial claim.

One possible explanation for the apparent contradiction between cross-sectional and longitudinal studies in teenage boys is that the impact of testosterone on sexual arousability has to go through stages of development, involving changes in receptor numbers or sensitivity influenced by individual differences in receptor sensitivity.

“One possible explanation for this apparent contradiction is that the impact of testosterone on sexual arousability (and hence behaviour) has to go through stages of development, which may involve changes in receptor numbers or sensitivity, a process which will also be influenced by individual differences in receptor sensitivity.”

May combine two claims.

Frequency of masturbation tends to follow the level of sexual interest, although cultural factors may influence this pattern of sexual expression.

“Frequency of masturbation tends to follow the level of sexual interest, although cultural factors may influence this pattern of sexual expression (Anderson et al. 1999).”

• cites Anderson et al. 1999 sourceNot checked — no full text of the source

May combine two claims.

In eugonadal men, intramuscular testosterone enanthate had no effect on sleep parameters and did not affect frequency, degree or duration of NPT when assessed as penile circumference, but did increase, modestly but significantly, penile rigidity during NPT.

“Intramuscular testosterone enanthate had no effect on sleep parameters, and did not affect frequency, degree or duration of NPT, when assessed as penile circumference, but did increase, modestly but significantly, penile rigidity during NPT.”

• cites Carani et al. (1995) sourceNot checked — no full text of the source

May combine two claims.

Reduction in sexual interest and enjoyment is common during the post-partum period, and is more marked in breast-feeding than bottle-feeding mothers.

“Reduction in sexual interest and enjoyment is common during the post-partum period, and is more marked in breast-feeding than bottle-feeding mothers (Alder & Bancroft 1988, Hyde & DeLamater 2000).”

• cites Alder & Bancroft 1988 sourceNot checked — no full text of the source
• cites Hyde & DeLamater 2000Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

The finding of lower testosterone and androstenedione in breast feeders with reduced sexual interest needs to be replicated.

“This finding needs to be replicated.”

May combine two claims.

Ovarian androgens start to decline a few years before the menopause, probably due to a reduction in the mid-cycle rise of testosterone.

“Ovarian androgens start to decline a few years before the menopause, probably due to a reduction in the mid-cycle rise of testosterone (Roger et al. 1980, Zumoff et al. 1995, Mushayandebvu et al. 1996).”

• cites Roger et al. 1980 sourceNot checked — no full text of the source
• cites Zumoff et al. 1995 sourceNot checked — no full text of the source
• cites Mushayandebvu et al. 1996 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S4 (based).

The role of testosterone in the emerging sexual arousability of the peri-pubertal male is not well understood.

“The role of testosterone in the emerging sexual arousability of the peri-pubertal male is not well understood.”

Classified as probably not a substantial claim.

The greater complexity of the reproductive endocrine system in women, who experience menstrual cycles, pregnancy and lactation and a clearly identifiable menopause, may account for the inconsistent evidence.

“This may result from the greater complexity of the reproductive endocrine system in women, who experience menstrual cycles, pregnancy and lactation and a clearly identifiable menopause.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Androgen production by the interstitial cells of the post-menopausal ovary is an important source of oestrogen from peripheral conversion.

“Androgen production by the interstitial cells of the post-menopausal ovary is an important source of oestrogen from peripheral conversion.”

Probably not a substantial claim: may not pass S1 (asserted).

If testosterone is important for sexual arousability in women, related temporal patterns of arousability through the cycle should be expected.

“Given this pattern, if testosterone is important for sexual arousability in women, we should expect to find related temporal patterns of arousability through the cycle.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

In the older male, the picture is complicated by various aging effects, including altered hypothalamo-pituitary feedback, increased testosterone binding and reduced receptor sensitivity.

“In the older male, the picture is complicated by various aging effects, including altered hypothalamo-pituitary feedback, increased testosterone binding and reduced receptor sensitivity.”

Probably not a substantial claim: may not pass S4 (based).

Once a woman settles into a pattern of regular ovulatory cycles, testosterone levels typically rise during the follicular phase and are at a maximum approximately for the middle third of the cycle, declining during the final third to reach a nadir during the first few days of the next follicular phase.

“However, once a woman settles into a pattern of regular ovulatory cycles, testosterone levels typically rise during the follicular phase and are at a maximum approximately for the middle third of the cycle, declining during the final third to reach a nadir during the first few days of the next follicular phase.”

May combine two claims.

In a study of 36 women who had not had sexual problems before starting cyproterone acetate, 16 (44%) reported negative effects on their sex life; this rises to 61% if women not in sexual relationships are excluded.

“Appelt & Strauss (1986) studied 36 women who had not had sexual problems before starting on CPA, and of these 16 (44%) reported negative effects on their sex life; this rises to 61% if women not in sexual relationships are excluded.”

• cites Appelt & Strauss (1986)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S2 (checkable).

To adequately test the androgen-behaviour relationship during the mid-life period, longitudinal studies are needed in which the baseline testosterone levels are assessed before the pre-menopausal decline.

“To adequately test the androgenbehaviour relationship during the mid-life period, longitudinal studies are needed in which the baseline testosterone levels are assessed before the pre-menopausal decline.”

May combine two claims.

The evidence points mainly to the effects of testosterone on central arousal mechanisms; the peripheral effects of testosterone in the human male relevant to sexual arousal are as yet unclear.

“The evidence points mainly to the effects of testosterone on central arousal mechanisms; the peripheral effects of testosterone in the human male, relevant to sexual arousal, are as yet unclear.”

May combine two claims.

In adult eugonadal men, the levels of testosterone in the circulation are substantially higher than required to maintain sexual arousability, suggesting that other effects of testosterone, most probably in the periphery, require higher levels than are needed in the central nervous system.

“It is also apparent that, in adult eugonadal men, the levels of testosterone in the circulation are substantially higher than required to maintain sexual arousability, suggesting that other effects of testosterone, most probably in the periphery, require higher levels than are needed in the central nervous system (CNS).”

May combine two claims.

It is difficult to predict which cases of erectile dysfunction are likely to benefit from testosterone, although low baseline levels of testosterone increase the likelihood.

“So far it has been difficult to predict which cases of ED are likely to benefit from testosterone, although low baseline levels of testosterone certainly increase the likelihood.”

May combine two claims.

The mid-to-late-follicular pattern of sexual interest is compatible with an effect of the rising testosterone during the follicular phase, although one might have expected a continuation of this testosterone effect into the first part of the luteal phase.

“This mid-to late-follicular pattern is compatible with an effect of the rising testosterone during the follicular phase, although one might have expected a continuation of this testosterone effect into the first part of the luteal phase.”

May combine two claims.

In pre-menopausal women, gonadotrophic stimulation of the interstitial cells is regulated by the negative feedback of ovarian steroids; the rise in LH that accompanies the menopausal transition may stimulate the interstitial cells to produce testosterone and androstenedione, sometimes excessively.

“Whereas in pre-menopausal women, gonadotrophic stimulation of the interstitial cells is regulated by the negative feedback of ovarian steroids, the rise in LH that accompanies the menopausal transition, resulting from the reduction in oestrogen-induced negative feedback, may stimulate the interstitial cells to produce testosterone and androstenedione, sometimes excessively.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

There is a lack of evidence of testosterone levels during the early cycles of post-menarcheal adolescents, which tend to be irregular and not predictably ovulatory.

“There is a lack of evidence of testosterone levels during the early cycles of post-menarcheal adolescents, which tend to be irregular and not predictably ovulatory.”

May combine two claims.

In a placebo-controlled study of women who had been sterilized or whose partners had been sterilized, a substantial minority of women on the combined OC reported a decline in sexual interest and enjoyment, an effect not observed with a low-dose progestagen only method.

“Graham et al. (1995), in a placebocontrolled study of women who had been sterilized or whose partners had been sterilized, found that a substantial minority of women on the combined OC reported a decline in sexual interest and enjoyment, an effect not observed with a low-dose progestagen only method.”

• cites Graham et al. (1995) sourceNot checked — no full text of the source

May combine two claims.

Two principal mechanisms are involved in lowering free testosterone by combined oral contraceptives: the mid-cycle rise in testosterone is blocked by suppression of ovulation and the associated pattern of gonadal steroid change, and the combined OC increases SHBG levels and hence reduces the free testosterone available.

“Two principle mechanisms are involved: the mid-cycle rise in testosterone is blocked by suppression of ovulation and the associated pattern of gonadal steroid change and the combined OC increases SHBG levels and hence reduces the free testosterone available.”

May combine two claims.

Increasing levels of testosterone occur in girls as they approach and go through puberty, but the changes are much less substantial than in the male; testosterone effectively doubles through pubertal maturation in girls compared with an 18-fold increase in boys.

“Testosterone starts at a lower level in the infant girl, and effectively doubles through pubertal maturation, compared with an 18-fold increase in testosterone for boys.”

Classified as probably not a substantial claim.

The inconsistent findings on testosterone and sexuality through the cycle could result from substantial individual variability in testosterone/behaviour relationships.

“But these inconsistent findings, involving studies with relatively small numbers of participants, could result from substantial individual variability in testosterone/behaviour relationships.”

May combine two claims.

In a cross-sectional study of eighth to tenth grade girls, there was a relation between testosterone levels and measures of sexual interest and masturbation, but not with the likelihood of having experienced sexual intercourse.

“As with their studies on adolescent boys, they found discrepant results between their cross-sectional study of eighth to tenth grade girls (approximately 13-15 years of age), where they found a relation between testosterone levels and measures of sexual interest and masturbation, but not with the likelihood of having experienced sexual intercourse”

• cites Udry et al. (1986) sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S4 (based).

With surgical removal of the ovaries there is an immediate and substantial drop in circulating androgens.

“With surgical removal of the ovaries there is an immediate and substantial drop in circulating androgens.”

May combine two claims.

In both OC studies, lowered testosterone levels could be the explanation, but as yet there is no direct evidence of the relation between testosterone levels and sexual interest.

“In both of these studies, lowered testosterone levels could be the explanation.As yet, however, we have no direct evidence of the relation between testosterone levels and sexual interest.”

May combine two claims.

The drop in sexual activity during menstruation does not necessarily mean that sexual arousability is at its lowest at that stage; there are a number of other non-hormonal explanations for the drop.

“However, this does not necessarily mean that sexual arousability is at its lowest at that stage; there are a number of other non-hormonal explanations for the drop in sexual activity during menstruation.”

May combine two claims.

In a sample of oophorectomized women, approximately 50% reported loss of sexual interest, which suggests that around 50% of women can undergo depletion of ovarian steroids and not experience loss of sexual interest.

“Approximately 50% of women came into this category, which suggests that around 50% of women can undergo this depletion of ovarian steroids and not experience loss of sexual interest.”

• cites Nathorst-Böös et al. (1993) sourceNot checked — no full text of the source

May combine two claims.

There is little evidence that DHEA is directly relevant to sexuality in either men or women, whereas it may be relevant to well-being and energy, and hence secondarily to sexual arousability.

“There is little evidence, however, that DHEA is directly relevant to sexuality in either men or women, whereas it may be relevant to well-being and energy, and hence secondarily to sexual arousability (Cawood & Bancroft 1996).”

• cites Cawood & Bancroft 1996 sourceNot checked — no full text of the source

May combine two claims.

Testosterone acts through signalling pathways that differ either in specific brain areas, or within different cells from the same area.

“They concluded that testosterone acts through signalling pathways that differ either in specific brain areas, or within different cells from the same area.”

• cites Roselli et al. (2001) sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Testosterone activity is mediated by androgen receptors in the lateral septal, pre-mamillary and intercalated mamillary nuclei.

“In contrast, testosterone activity was thought to be mediated by androgen receptors in the lateral septal, pre-mamillary and intercalated mamillary nuclei.”

• cites Michael et al. (1989) sourceNot checked — no full text of the source

May combine two claims.

In male rhesus monkeys, 5-alpha-reductase activity is fairly evenly distributed in the brain, whereas aromatase activity is much more localized.

“They found 5 -reductase activity to be fairly evenly distributed in the brain, whereas, in contrast, aromatase activity was much more localized.”

• cites Michael et al. (1989) sourceNot checked — no full text of the source

May combine two claims.

Androstenedione has a substantial capacity for conversion to both oestradiol and testosterone; DHEA has a very limited capacity for conversion to testosterone.

“Androstenedione has a substantial capacity for conversion to both oestradiol and testosterone; dehydroepiandrosterone (DHEA) has a very limited capacity for conversion to testosterone.”

May combine two claims.

Carney et al. (1978) found some benefit of testosterone when combined with counselling for couples whose main problem was sexual unresponsiveness of the woman, but other comparable studies failed to replicate this effect.

“Although Carney et al. (1978) found some benefit of testosterone when combined with counselling for couples whose main problem was sexual unresponsiveness of the woman, other comparable studies failed to replicate this effect (Mathews et al. 1983, Dow & Gallasher 1989).”

• cites Carney et al. (1978) sourceNot checked — no full text of the source
• cites Mathews et al. 1983 sourceNot checked — no full text of the source
• cites Dow & Gallasher 1989 sourceNot checked — no full text of the source

May combine two claims.

In a placebo-controlled study of women with adrenal insufficiency, the addition of DHEA to corticosteroid replacement improved measures of sexual interest and responsiveness as well as mood and general well-being, although the effects on mood were more substantial.

“In a placebo-controlled study of women with adrenal insufficiency, the addition of DHEA to the corticosteroid replacement improved measures of sexual interest and responsiveness as well as mood and general well-being, although the effects on mood were more substantial (Arlt et al. 1999).”

• cites Arlt et al. 1999 sourceNot checked — no full text of the source

May combine two claims.

In a study of eight young amenorrhoeic women with low weight, they showed lower levels of sexual interest and activity, and lower testosterone levels than a comparison group of normally menstruating aged-matched women.

“In a more experimental study, Tuiten et al. (1996) studied eight young amenorrhoeic women with low weight, although none had the diagnosis of anorexia nervosa.They showed lower levels of sexual interest and activity, and lower testosterone levels than a comparison group of normally menstruating aged-matched women.”

• cites Tuiten et al. (1996) sourceNot checked — no full text of the source

May combine two claims.

Whereas there is evidence that testosterone withdrawal and/or replacement can have effects on women's sexuality, the evidence is inconsistent and sometimes contradictory.

“Whereas there is evidence that testosterone withdrawal and/or replacement can have effects on women's sexuality, the evidence is inconsistent and sometimes contradictory.”

May combine two claims.

In a placebo-controlled evaluation of DHEA administration to women between 40 and 70 years, there was significant improvement in a somewhat crude measure of well-being, but no effect on 'libido'.

“In a placebo-controlled evaluation of DHEA administration to women between 40 and 70 years (Morales et al. 1994b), there was significant improvement in a somewhat crude measure of well-being, but no effect on 'libido'.”

• cites Morales et al. 1994bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Research on the site of action of testosterone in the non-human primate brain has been ongoing for more than 30 years, during which time there have been major changes in the technologies used.

“Research on the site of action of testosterone in the non-human primate brain has been ongoing for more than 30 years, during which time there have been major changes in the technologies used, and these have to be kept in mind when comparing findings across studies.”

May combine two claims.

In the same study, the effect of testosterone on vaginal pulse amplitude was not reflected in subjective ratings of arousal, and the two treatments did not differ in daily ratings of sexuality or mood.

“However, this effect was not reflected in subjective ratings of arousal.Nor did the two treatments differ in terms of daily ratings of sexuality or mood.”

• cites Tuiten et al. (1996) sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

For both non-human primates and humans, the majority of evidence on androgen receptors is from males.

“For both non-human primates and humans, the majority of evidence is from males.”

May combine two claims.

This experiment demonstrated an effect of increasing testosterone on physiological response to erotic stimulation, which was not apparent in any subjective or mood measures.

“This experiment therefore demonstrated an effect of increasing testosterone on physiological response to erotic stimulation, which was not apparent in any subjective or mood measures.”

Probably not a substantial claim: may not pass S3 (load-bearing).

This is the only study in which testosterone administration on its own has been evaluated.

“This is the only study in which testosterone administration on its own has been evaluated.”

May combine two claims.

Functional brain imaging is still at an early stage, with methodological inconsistencies across studies making interpretation more difficult.

“Functional brain imaging promises to throw considerable light on brain activity related to sexual function, but is still at an early stage of development, with methodological inconsistencies across studies making interpretation of the findings more difficult (Sumich et al. 2003, Mouras & Stoleru 2005).”

• cites Sumich et al. 2003 sourceNot checked — no full text of the source
• cites Mouras & Stoleru 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Roselli & Klosterman (1998) concluded that the male pattern of aromatization in the rat is established perinatally and probably forms a fundamental component of masculinization.

“Roselli & Klosterman (1998) concluded from their findings that this male pattern of aromatization in the rat is established perinatally, and probably forms a fundamental component of masculinization.”

• cites Roselli & Klosterman (1998) sourceNot checked — no full text of the source

May combine two claims.

Whereas testosterone may play a role in the sexuality of many women, its effects can easily be obscured by the co-existence of other psychological or affective factors.

“Thus, whereas testosterone may play a role in the sexuality of many women, its effects can easily be obscured by the co-existence of other psychological or affective factors.”

The quote only partly states this claim.

In the amenorrhoeic women, vaginal pulse amplitude in response to film was significantly greater in the testosterone-treated condition than in placebo.

“VPA was significantly greater in response to film in the testosterone-treated condition.”

• cites Tuiten et al. (1996) sourceNot checked — no full text of the source

May combine two claims.

Finley & Kritzer (1999) found androgen receptor protein in the pre-frontal cortex of rhesus monkeys and found no sex differences in this respect.

“Finley & Kritzer (1999), reporting the presence of androgen receptor protein in the pre-frontal cortex of rhesus monkeys, found no differences between their male and female monkeys in this respect.”

• cites Finley & Kritzer (1999)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Neuropeptides are produced in substantial amounts within the CNS.

“Although peptides are released in many different parts of the body, neuropeptides are produced in substantial amounts within the CNS.”

May combine two claims.

There are few directly relevant data on the speed of action of androgens in humans, although one study in women showed an effect on genital response within 3 to 4 h.

“As yet we have few directly relevant data on the speed of action of androgens in the human, although one study in women, discussed earlier (Tuiten et al. 2000), showed an effect on genital response within 3 to 4 h.”

• cites Tuiten et al. 2000 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Mas et al. (1995) concluded that DA blockade is also involved in sexual satiety and, because of interactions, could be the key factor.

“Mas et al. (1995) concluded that DA blockade was also involved and, because of the interaction between dopaminergic, serotonergic and norepinephric mechanisms, could be the key factor.”

• cites Mas et al. (1995)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Bancroft et al. (1974) found that both ethinyl oestradiol and CPA reduced sexual interest, masturbatory activity and erectile response to erotic fantasies and slides in incarcerated sexual offenders, producing a pattern similar to hypogonadal men.

“Both compounds reduced sexual interest, masturbatory activity and erectile response to erotic fantasies and slides producing a pattern very similar to that found in hypogonadal men.”

• cites Bancroft et al. (1974) sourceNot checked — no full text of the source

Classified as probably not a substantial claim.

Whether oestradiol has a direct effect on sexual interest and arousability remains unclear.

“However, whether oestradiol has a direct effect on sexual interest and arousability remains unclear.”

May combine two claims.

In women masturbating to orgasm, low doses of naloxone enhanced pleasure during orgasm while higher doses reduced sexual arousal and orgasmic pleasure.

“A dual dose-related effect was observed in women masturbating to orgasm (Gillman & Lichtigfield 1983); low doses of naloxone enhanced pleasure during orgasm, while higher doses had the opposite effect, reducing sexual arousal as well as orgasmic pleasure.”

• cites Gillman & Lichtigfield 1983 sourceNot checked — no full text of the source

May combine two claims.

The sexual inhibiting effects of endorphin are believed to occur mainly through action on the pre-optic area and amygdala, with the precise effect depending on the site of infusion.

“The sexual inhibiting effects of -endorphin, and related opiate peptides, are believed to occur mainly through their action on the pre-optic area and the amygdala, the precise inhibiting effect depending on the site of infusion.”

May combine two claims.

Carmichael et al. (1987) found plasma OT increased around orgasm in men and women, remaining raised for at least 5 min after orgasm.

“Carmichael et al. (1987) found that plasma OT increased around the time of orgasm in men and women, remaining raised for at least 5 min after orgasm.”

• cites Carmichael et al. (1987) sourceNot checked — no full text of the source

May combine two claims.

In women, a substantial proportion of androgen production is from the adrenal glands, so increased adrenal androgens can be expected in states of increased adrenal activity such as anxiety, stress or depression.

“In women, a substantial proportion of androgen production is from the adrenal glands and hence increased adrenal androgens can be expected in states associated with increased adrenal activity, such as anxiety, stress or depression (e.g.Weber et al. 2000).”

• cites Weber et al. 2000 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Kruger et al. (2002) postulated that the post-orgasmic rise in PRL acts as a feedback control of sexual drive, contributing to the post-orgasmic refractory period.

“These apparently consistent recent results have led these researchers to postulate that the post-orgasmic rise in PRL acts as a feedback control of sexual drive, contributing to the post-orgasmic refractory period (Kruger et al. 2002).”

• cites Kruger et al. 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

In men, naloxone produced partial erection in three of six men, and the combination of yohimbine and naloxone produced full and prolonged erection in all six.

“Yohimbine on its own produced no observable effect, whereas naloxone produced partial erection in three of the six men studied.The combination of the two drugs, however, produced a full and prolonged erection in all of the six men.”

• cites Charney & Heninger (1986) sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

There is consistent evidence of the importance of oestradiol for normal vaginal lubrication.

“There is consistent evidence of the importance of oestradiol for normal vaginal lubrication.”

May combine two claims.

In male rats, serotonin increases in the lateral hypothalamic area during the post-ejaculatory interval, and injecting a serotonin reuptake inhibitor into the lateral hypothalamus produces behavioural effects similar to the post-ejaculatory interval.

“Lorrain et al. (1997) showed in male rats that, during the post-ejaculatory interval, serotonin increased in the lateral hypothalamic area.Injecting a serotonin reuptake inhibitor into the lateral hypothalamus produced behavioural effects similar to the post-ejaculatory interval.”

• cites Lorrain et al. (1997) sourceNot checked — no full text of the source

May combine two claims.

Animal evidence is consistent with both peripheral and central roles for OT; the peripheral effect is facilitation of smooth muscle contraction, and the central role is more as a neuromodulator in various response systems.

“Thus, so far the animal evidence is consistent with both a peripheral and central role for OT; the most obvious peripheral effect being facilitation of smooth muscle contraction -the central role being more as a neuromodulator in a variety of response systems.”

May combine two claims.

OT knockout mice show clear impairment of milk let-down but no apparent impairment of mating or parturition.

“OT knockout mice show clear impairment of milk let-down, but no apparent impairment of either mating or parturition (Nishimori et al. 1996, Young et al. 1996).”

• cites Nishimori et al. 1996 sourceNot checked — no full text of the source
• cites Young et al. 1996Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Evidence for testosterone effects is more consistent for males than females; a potentially important factor is greater variability of behavioural responsiveness to androgens among women.

“The evidence is more consistent for the male than for the female.Apart from methodological considerations, which are more complex in women than in men, potentially the most important factor accounting for this gender difference is a greater variability of behavioural responsiveness to androgens among women.”

May combine two claims.

Exogenous opiates such as morphine and heroin reduce sexual interest, impair genital response and block ejaculation and orgasm, with reversal during withdrawal.

“widespread awareness of the negative effects of exogenous opiates, such as morphine and heroin, on the sexuality of male and female drug addicts, reducing sexual interest, impairing genital response and blocking ejaculation and orgasm, with active and spontaneous reversal of such effects often occurring during opiate withdrawal (for review see Pfaus & Gorzalka 1987).”

• cites Pfaus & Gorzalka 1987 sourceNot checked — no full text of the source

May combine two claims.

Chronic exposure to elevated PRL in rats causes predictable impairment of sexual response with increased intromission and ejaculation latencies and reduction in reflexive erections.

“The evidence from chronic exposure, typically implemented by means of transplants of pituitary glands, indicates that after a week or longer there is predictable impairment of sexual response with increased intromission and ejaculation latencies, and reduction in reflexive erections in male rats (Meisel & Sachs 1994).”

• cites Meisel & Sachs 1994Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim. May combine two claims.

Rodriguez-Manzo & Fernando-Guasti concluded that NE, serotonergic and opiate mechanisms are all involved in sexual satiety, with the NE system playing a key role.

“They concluded that norepinephric (NE), serotonergic and opiate mechanisms were all involved, but with the NE system playing a key role.”

• cites Rodriguez-Manzo & Fernando-Guasti (1994, 1995)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Opiates inhibit LH-releasing hormone and reduce LH and testosterone, but animal evidence shows the sexually inhibiting effects are predominantly independent of this reduction.

“The picture is complicated by the fact that opiates inhibit LH-releasing hormone, and hence reduce LH and testosterone.However, the animal evidence shows that the sexually inhibiting effects are predominantly independent of this reduction of testosterone.”

May combine two claims.

Impaired sexual desire can occur in hyperprolactinaemia without obvious gonadal steroid deficiency, focusing attention on negative sexual effects of PRL.

“Although hyperprolactinaemia is also commonly associated with testosterone deficiency in men and ovarian dysfunction in women, impaired sexual desire can occur in hyperprolactinaemia without obvious gonadal steroid deficiency.This has focused attention on the negative sexual effects of PRL.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

More than 90% of testosterone in males is produced by the testes.

“More than 90% of testosterone in the male is produced by the testes.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

It remains possible that androgens produce a relatively rapid membrane-mediated effect by means of aromatization.

“It remains a possibility that androgens may produce a relatively rapid membranemediated effect by means of aromatization.”

May combine two claims.

In animal studies, centrally administered OT has induced erection, apparently testosterone dependent, and OT receptor antagonists can prevent non-contact erections.

“In animal studies, centrally administered OT has induced erection, an effect which is apparently testosterone dependent, and OT receptor antagonists can prevent non-contact erections, considered an index of sexual arousal (Argiolas 1999).”

• cites Argiolas 1999Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Whether the increase of OT around orgasm has any specific function, rather than being an epiphenomenon, remains uncertain.

“Whether the increase of OT around orgasm, which has been somewhat inconsistently observed in the human literature, has any specific function, rather than being an epiphenomenon of other changes, remains uncertain”

May combine two claims.

The limbic system is characterized by peptidergic neurotransmission, contrasting with the synaptic neuronal structure of the cortex.

“The limbic system is characterized by peptidergic neurotransmission, contrasting with the synaptic neuronal structure of the cortex (Herbert 1993)”

• cites Herbert 1993 sourceNot checked — no full text of the source

May combine two claims.

In humans, low sexual desire is a common symptom of hyperprolactinaemia, often associated with erectile problems in men.

“In the human, low sexual desire is a common symptom of hyperprolactinaemia, often associated, in men, with erectile problems (Franks & Jacobs 1983).”

• cites Franks & Jacobs 1983 sourceNot checked — no full text of the source

May combine two claims.

In recent studies, a clear increase in PRL was observed following orgasm in both men and women, with levels still raised after 60 min, but not in men who masturbated without ejaculating.

“in a recent series of studies in which masturbation or sexual activity with a partner led to orgasm or ejaculation, a clear increase in PRL was observed following orgasm in both men (Kruger et al. 1998(Kruger et al. , 2003a) ) and women (Exton et al. 1999), with levels still raised after 60 min.This pattern was not found in a parallel study of men who masturbated without ejaculating (Kruger et al.”

• cites Kruger et al. 1998 sourceNot checked — no full text of the source
• cites Kruger et al. 2003aNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Exton et al. 1999 sourceNot checked — no full text of the source

May combine two claims.

CPA substantially reduced total testosterone with no change in SHBG, whereas EE substantially increased both total testosterone and SHBG.

“although CPA substantially reduced total testosterone, with no change in SHBG, EE substantially increased both total testosterone and SHBG (Murray et al. 1975).”

• cites Murray et al. 1975 sourceNot checked — no full text of the source

May combine two claims.

In males, there is a threshold below the normal physiological range above which increased testosterone has little behavioural effect and below which signs of androgen deficiency are likely; this threshold concept does not appear to apply to women.

“In the male, the evidence points to a threshold, below the normal physiological range, above which increased testosterone levels have little behavioural effect, and below which signs of androgen deficiency are likely to occur.This threshold concept does not appear to apply to women.”

May combine two claims.

In other species, the role of oestradiol in mediating many CNS effects of testosterone on male sexual behaviour is well established, but its role in human male sexuality remains unclear.

“Whereas in other species, the role of oestradiol in mediating many of the central nervous system effects of testosterone on male sexual behaviour is well established (Lindzey & Korach 2003), its role in human male sexuality remains unclear”

• cites Lindzey & Korach 2003Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

PRL is secreted by the anterior pituitary into the general circulation, showing a diurnal episodic pattern maximal during sleep.

“PRL is secreted by the anterior pituitary into the general circulation, showing a diurnal episodic pattern, maximal during sleep.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The conventional view is that androgens act in the brain via genomic effects.

“The conventional view is that androgens act in the brain via genomic effects (Rommerts 1990).”

• cites Rommerts 1990 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S4 (based).

Exogenous and endogenous sources of oestradiol may have fundamentally different effects, particularly when endogenous oestradiol results from aromatization of testosterone within the brain.

“with the possibility that exogenous and endogenous sources of oestradiol have fundamentally different effects, particularly when the endogenous oestradiol results from aromatization of testosterone within the brain.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

It is generally accepted that OT plays a key role during lactation, facilitating the milk ejection reflex.

“It is generally accepted that OT plays a key role during lactation, facilitating the milk ejection reflex.”

May combine two claims.

Gooren (1985) found that in eugonadal men tamoxifen and testolactone had no adverse sexual effects, and that DHT was as effective as testosterone in maintaining sexuality in hypogonadal men.

“Gooren (1985) found that, in eugonadal men, the oestrogen receptor antagonist, tamoxifen, and the aromatase inhibitor, testolactone, had no adverse sexual effects, and that dihydrotestosterone (DHT) was as effective as testosterone in maintaining sexuality in hypogonadal men.”

• cites Gooren (1985) sourceNot checked — no full text of the source

May combine two claims.

In male rats, sexual satiety occurs after unrestricted access to receptive females, develops on average after seven copulations, and return to normal responsiveness takes around 15 days.

“Attention is also being paid to a related phenomenon, 'sexual satiety' which, in male rats, occurs after a series of unrestricted access to receptive females.This state of sexual unresponsiveness develops, on average, after seven copulations and return to normal responsiveness takes around 15 days.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Wallen & Parsons (1998) advocated that the sexual effects of testosterone in women result from the consequent increase in free oestradiol, supporting this with experimental data from rhesus monkeys.

“Wallen & Parsons (1998) have strongly advocated that the sexual effects of testosterone in women result from the consequent increase in free oestradiol, supporting this conclusion with experimental data from rhesus monkeys.”

• cites Wallen & Parsons (1998)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

DA in the tubero-infundibular dopaminergic system maintains inhibitory control of PRL release; reduction of DA activity increases PRL release.

“DA in the tubero-infundibular dopaminergic system maintains inhibitory control of PRL release.Thus any reduction of DA activity in this system will result in increased PRL release.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

In humans, the refractory period is more substantial in males than females.

“In humans, the refractory period is more substantial in the male than the female.”

May combine two claims.

The complexity of peptide function reflects widespread interaction between peptides and other neuro-mediators and the phylogenetically primitive nature of peptides, which could account for overlapping functions where one function can be carried out by more than one peptide.

“This reflects in part the widespread interaction between peptides and other neuro-mediators, but also the phylogenetically primitive nature of peptides, which could account for their having overlapping functions, in many cases, where one function can be carried out by more than one peptide.”

May combine two claims.

For peptides, some conventional hormonal functions are evident, but research into peptide function confronts increasing complexity that makes hormonal explanations of peptide function less and less helpful.

“Some conventional 'hormonal' functions are evident for several of the peptides (e.g.PRL and lactation), but research into the role of peptides confronts us with an ever-increasing complexity which makes 'hormonal' explanations of peptide function less and less helpful.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The dual control model of sexual behaviour postulates parallel function and interaction of sexual excitatory and inhibitory systems in the brain.

“We have built on Gray's model with our dual control model of sexual behaviour, which postulates parallel function and interaction of sexual excitatory and inhibitory systems in the brain (Bancroft 1999, Bancroft & Janssen 2000).”

• cites Bancroft 1999 sourceNot checked — no full text of the source
• cites Bancroft & Janssen 2000 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

With no such desensitization in females, basic genetic variability would be more evident at much lower levels of testosterone and manifested as greater variability in behavioural responsiveness from early adolescent development or adrenarche onwards.

“(5) With no such desensitization in females, the basic genetic variability would be more evident, at much lower levels of testosterone, and manifested as greater variability in behavioural responsiveness, demonstrated from early adolescent development (or adrenarche) onwards.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

Effects of testosterone on mood and general arousability may be relevant to sexual arousal indirectly.

“Effects on mood and general arousability may be relevant to sexual arousal indirectly.”

May combine two claims.

The concept of 'hormone' remains relevant to the role of gonadal steroids, in particular testosterone, in understanding sexual arousal, although there are uncertainties about how these hormonal effects are mediated at the target organ.

“The concept clearly remains relevant to the role of gonadal steroids, in particular testosterone, even though there are a number of uncertainties about how these 'hormonal' effects are mediated at the target organ.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Possible consequences of desensitization in the male include that genetically determined variations in CNS receptor responsiveness to androgens across individuals are flattened out and hence less evident, and that much higher levels of testosterone from puberty onwards are possible without hyperstimulation of CNS mechanisms.

“(4) Possible consequences of such desensitization in the male include that (i) genetically determined variations in CNS receptor responsiveness to androgens, across individuals, are 'flattened out' and hence less evident and (ii) much higher levels of testosterone from puberty onwards are possible without hyperstimulation of CNS mechanisms.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Greater variability in sensitivity to androgens in women could result from greater genetic variability in women, because behavioural responsiveness to gonadal steroids is less crucial to reproduction in women than in men.

“(1) The greater variability in the sensitivity to androgens in women could result from a greater genetic variability in women, on the grounds that in women behavioural responsiveness to gonadal steroids is less crucial to reproduction than is the case with men.”

• AssumptionRests on an assumption: There is a striking difference in the sensitivity of the female and male brain to testosterone.
• AssumptionRests on an assumption: In women, behavioural responsiveness to gonadal steroids is less crucial to reproduction than in men.

May combine two claims.

Females with congenital adrenal hyperplasia (CAH), particularly the salt-losing variety associated with higher fetal testosterone, show some masculinization of behaviour and low levels of sexual interest and activity associated with low fertility.

“For example, females with congenital adrenal hyperplasia (CAH), particularly the salt-losing variety which is associated with higher levels of testosterone during fetal development, show not only some degree of masculinization of behaviour, but also low levels of sexual interest and activity associated with low fertility (Meyer-Bahlburg 1999).”

• cites Meyer-Bahlburg 1999Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S4 (based).

Exposure to substantially higher levels of testosterone during fetal development and during the first few weeks post-natally could be responsible for desensitizing the CNS to testosterone effects in the male.

“(3) Exposure to substantially higher levels of testosterone during fetal development and also during the first few weeks post-natally could be responsible for desensitizing the CNS to testosterone effects in the male.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Inhibition of sexual response is adaptive for the majority, preventing sexual arousal in circumstances perceived as dangerous or risky, and the post-ejaculatory refractory period ensures fertility is not impaired by too frequent ejaculations.

“From this perspective, inhibition of sexual response, for the majority, is adaptive, preventing sexual arousal in circumstances that are perceived to be dangerous or risky, or in the case of the post-ejaculatory refractory period, ensuring that fertility is not impaired by too frequent ejaculations (all adaptive patterns of obvious relevance across species).”

May combine two claims.

If males were as sensitive to the CNS effects of testosterone as females, the behavioural effects of masculinizing testosterone levels would be maladaptive, so there is a need in males to reduce responsiveness to androgen effects in the brain.

“It is postulated that if males were as sensitive to the CNS effects of testosterone as females, then the behavioural effects of these masculinizing levels would be maladaptive.Hence there is a need in the male to reduce responsiveness to androgen effects in the brain.”

• AssumptionRests on an assumption: Greater levels of testosterone in men are necessary for masculinizing effects such as increased growth and muscle bulk, dependent on the peripheral anabolic effects of testosterone.