The endocrinology of sexual arousal

In the paper

“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).”

What the sources say

• Supported

  Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Shifren et al. (2000) source

In the paper

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

What the sources say

• ?Not matched

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

  cites Parmeggiana & Morrison 1990

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Carani et al. 1995 source

In the paper

“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.”

In the paper

“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.”

What the sources say

• ?Not matched

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

  cites Bagatell et al. (1994b)
• ?Not checked — no full text of the sourcecites Yates et al. (1999) source

In the paper

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

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Buena et al. (1993) source

In the paper

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

In the paper

“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.”

In the paper

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

In the paper

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

In the paper

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

In the paper

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

In the paper

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

In the paper

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

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Udry et al. 1985 source

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Anderson et al. (1992) source

In the paper

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

In the paper

“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.”

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Anderson et al. 1999 source

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Carani et al. (1995) source

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Alder & Bancroft 1988 source
• ?Not matched

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

  cites Hyde & DeLamater 2000

In the paper

“This finding needs to be replicated.”

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Roger et al. 1980 source
• ?Not checked — no full text of the sourcecites Zumoff et al. 1995 source
• ?Not checked — no full text of the sourcecites Mushayandebvu et al. 1996 source

In the paper

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

In the paper

“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.”

In the paper

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

In the paper

“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.”

In the paper

“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 paper

“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.”

In the paper

“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.”

What the sources say

• ?Not matched

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

  cites Appelt & Strauss (1986)

In the paper

“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.”

In the paper

“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.”

In the paper

“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).”

In the paper

“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.”

In the paper

“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.”

In the paper

“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.”

In the paper

“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.”

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Graham et al. (1995) source

In the paper

“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.”

In the paper

“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.”

In the paper

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

In the paper

“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”

What the sources say

• ?Not checked — no full text of the sourcecites Udry et al. (1986) source

In the paper

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

In the paper

“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.”

In the paper

“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.”

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Nathorst-Böös et al. (1993) source

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Cawood & Bancroft 1996 source

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Roselli et al. (2001) source

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Michael et al. (1989) source

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Michael et al. (1989) source

In the paper

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

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Carney et al. (1978) source
• ?Not checked — no full text of the sourcecites Mathews et al. 1983 source
• ?Not checked — no full text of the sourcecites Dow & Gallasher 1989 source

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Arlt et al. 1999 source

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Tuiten et al. (1996) source

In the paper

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

In the paper

“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'.”

What the sources say

• ?Not matched

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

  cites Morales et al. 1994b

In the paper

“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.”

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Tuiten et al. (1996) source

In the paper

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

In the paper

“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.”

In the paper

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

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Sumich et al. 2003 source
• ?Not matched

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

  cites Mouras & Stoleru 2005

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Roselli & Klosterman (1998) source

In the paper

“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.”

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Tuiten et al. (1996) source

In the paper

“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.”

What the sources say

• ?Not matched

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

  cites Finley & Kritzer (1999)

In the paper

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

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Tuiten et al. 2000 source

In the paper

“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.”

What the sources say

• ?Not matched

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

  cites Mas et al. (1995)

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Bancroft et al. (1974) source

In the paper

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

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Gillman & Lichtigfield 1983 source

In the paper

“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.”

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Carmichael et al. (1987) source

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Weber et al. 2000 source

In the paper

“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).”

What the sources say

• ?Not matched

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

  cites Kruger et al. 2002

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Charney & Heninger (1986) source

In the paper

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

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Lorrain et al. (1997) source

In the paper

“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.”

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Nishimori et al. 1996 source
• ?Not matched

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

  cites Young et al. 1996

In the paper

“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.”

In the paper

“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).”

What the sources say

• ?Not checked — no full text of the sourcecites Pfaus & Gorzalka 1987 source

In the paper

“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).”

What the sources say

• ?Not matched

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

  cites Meisel & Sachs 1994

In the paper

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

What the sources say

• ?Not matched

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

  cites Rodriguez-Manzo & Fernando-Guasti (1994, 1995)

In the paper

“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.”

In the paper

“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.”

In the paper

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

In the paper

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

In the paper

“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).”

What the sources say

• ?Not matched

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

  cites Argiolas 1999

In the paper

“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”

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Herbert 1993 source

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Franks & Jacobs 1983 source

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Kruger et al. 1998 source
• ?Not matched

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

  cites Kruger et al. 2003a
• ?Not checked — no full text of the sourcecites Exton et al. 1999 source

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Murray et al. 1975 source

In the paper

“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.”

In the paper

“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”

What the sources say

• ?Not matched

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

  cites Lindzey & Korach 2003

In the paper

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

In the paper

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

What the sources say

• ?Not checked — no full text of the sourcecites Rommerts 1990 source

In the paper

“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.”

In the paper

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

In the paper

“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.”

What the sources say

• ?Not checked — no full text of the sourcecites Gooren (1985) source

In the paper

“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.”

In the paper

“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.”

What the sources say

• ?Not matched

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

  cites Wallen & Parsons (1998)

In the paper

“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.”

In the paper

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

In the paper

“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.”

In the paper

“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.”