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Oxytocin is clearly involved in human reproduction and serves an important role in sexual arousal. Oxytocin serum levels were measured before and after sexual stimulation in 12 healthy women. Values of oxytocin 1 min after orgasm were significantly higher (p < 0.05) than baseline levels. This finding supports the hypothesis that oxytocin plays a major part in human sexual response both in neuroendocrine function and postcoital behavior.
Original Paper
Gynecol Obstet Invest 1999;47:125–126
The Role of Oxytocin in Relation to
Female Sexual Arousal
Wibke BlaicheraDoris GruberaChristian BieglmayeraAlex M. Blaicherb
Wolfgang KnogleraJohannes C. Hubera
Department of aGynecology and Obstetrics, Division of Gynecological Endocrinology and Reproduction Medicine,
and bDepartment of Anesthesiology and General Intensive Care, University of Vienna, Austria
Received: March 17, 1998
Accepted: May 5, 1998
Wibke Blaicher, MD
PO Box 41
A–1097 Vienna (Austria)
Fax +43 1 409 51 51, E-Mail
Fax + 41 61 306 12 34
© 1999 S. Karger AG, Basel
Accessible online at: /karger
Key Words
Oxytocin W Human W Sexual arousal
Oxytocin is clearly involved in human reproduction and
serves an important role in sexual arousal. Oxytocin
serum levels were measured before and after sexual
stimulation in 12 healthy women. Values of oxytocin
1 min after orgasm were significantly higher (p ! 0.05)
than baseline levels. This finding supports the hypothe-
sis that oxytocin plays a major part in human sexual
response both in neuroendocrine function and postcoital
Oxytocin (OXY) serves an important role in the sec-
ond stage of labor [1] as well as in the lactokinetic reflex
with nipple stimulation during breast-feeding [2]. It is
supposed to rise during sexual arousal and peak during
orgasm in women and in men, which is possibly the
response to areolae or genital tract stimulation. As pre-
vious studies demonstrated, there are variations in OXY
levels as well as of female sexual interest during the men-
strual cycle [3]. OXY peaks at time of ovulation and
remains significantly elevated in the follicular phase when
compared to the luteal phase [4].
Although the nature of the interaction between OXY
and other hormones in the process of female sexual arous-
al, receptivity, and maternal behavior is not clear, the
OXY-releasing effect of genital tract stimulation has been
described in animal models [5, 6].
The purpose of the investigation was to quantify serum
OXY concentration in relationship to sexual arousal in
human females.
Materials and Methods
After the approval of the institutional review board and written
informed consent, we investigated 12 healthy unmedicated females
aged 23–37 years with regular ovulatory cycles (mean 28 B 4 days).
Ovulation was confirmed by a progesterone serum level 13 ng/ml
7 days before the expected menstruation cycle. The investigation was
performed on day 14 of the menstrual cycle. Venous blood samples
were collected before, exactly 1 and 5 min after masturbation.
OXY Analysis
Blood was allowed to run freely into chilled EDTA tubes. Trasylol
(0.5 ml) was added per 10 ml blood and the tubes were spun in a
refrigerated centrifuge. The plasma samples were stored at –70 °C.
OXY was measured with radioimmunoassay (RIA) kits from Phoe-
nix Pharmaceuticals, Mountain View, Calif., USA. We thawed the
plasma samples in an ice-bath and added 2 ml 1% trifluoroacetic
acid (TFA) to 2 ml plasma. These acidified samples were centrifuged
at 6,000 g for 30 min. C-18 columns (200 mg, Sep-Column, Phoenix)
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Gynecol Obstet Invest 1999;47:125–126
Table 1.
OXY values (in pg/ml) at baseline, exactly 1 and 5 min after
orgasm in 12 female volunteers
No. Baseline 1 min
after orgasm 5 min
after orgasm
23.6 42.9 28.2
2 10.4 11.7 8.1
3 13.7 14.9 17.0
4 8.6 9.2 8.9
5 8.6 10.3 11.7
6 8.3 10.0 8.1
7 20.0 20.8 22.8
8 17.8 18.6 18.3
9 8.6 8.8 6.9
10 6.2 6.9 5.2
11 4.9 6.3 7.9
12 6.9 7.6 7.7
were activated by passing through of 1 ml 60% acetonitrile (AN) in
1% TFA followed by three times 3 ml 1% TFA. The sample superna-
tants were layered on top of the activated columns and consecutively
the columns were washed twice with 3 ml 1% TFA. Peptides were
eluted by 3 ml 60% AN in 1% TFA. This solid phase extraction pro-
cedure was carried out automatically by an Aspec XL (Gilson,
France). Sample tubes as well as eluate tubes were kept cool at 4°C.
Duration of an activation and extraction cycle was about 20 min.
Eluates were evaporated at room temperature by GyroVap centri-
fuge (Howe, UK) and the residues were dissolved in 250 Ìl assay
buffer. For setting up the OXY RIA we followed the manufacturer’s
protocol. Radioactivity was measured by a crystal scintillation coun-
ter (Wizzard 1470; Wallac, Finland) and data reduction was per-
formed with the Multicalc software (Wallac).
The extraction yield of an OXY standard mixed with plasma was
190%. Linearity of the dilution behavior for extracts was tested and
there was no drift in results during sample extraction.
Statistical analysis was done using Wilcoxon’s test for paired sam-
ples with p ! 0.05 considered to be significant. Data are expressed as
mean B SD.
Each subject showed an OXY increase 1 min after
orgasm. At baseline the mean OXY serum level was 11.53
B 6.08 pg/ml and increased significantly to 14.00 B
10.00 pg/ml (p = 0.0033) 1 min after orgasm, and de-
creased at 5 min to 12.56 B 7.30 pg/ml. OXY levels of 5
subjects did not return to baseline levels 5 min postmas-
turbation (table 1).
Our measurements confirm animal research data, that
genital tract stimulation results in an increased OXY
release immediately after orgasm. Both OXY plasma lev-
els and nerve growth factor (NGF) plasma concentration
have been shown to increase during labor and lactation
[5]. These findings suggest that there is an interaction
between OXY and NGF which seems to play an impor-
tant role during labor and gestation as well as in terms of
sexual excitement and orgasm. Further research is neces-
sary to determine whether the intracoital OXY release has
a psychotropic dimension in respect of the ongoing rela-
tionship between man and woman. These findings may
lead to a new interpretation of sexual intercourse and
offer a new evolutional perspective.
1 Steer PJ: The endocrinology of parturition in
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Farley TMM, Pinol A: The relationship be-
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5 Anderson-Hunt M, Dennerstein L: Oxytocin
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6 Chan A, Dudley CA, Moss RL: Hormonal and
chemical modulation of ventromedial hypo-
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... Hypoestrogenic conditions, such as menopause, and postpartum due to inadequate lubrication and atrophy of the genitourinary system cause disruption of normal sexual function. Impaired oxytocin secretion reduces sexual excitement, rejection of sexual activity, and impaired response to sexual stimuli [3,[9][10][11]]. ...
... Because people with sexual problems may have hormonal disorders (such as oxytocin) in the hypothalamus-pituitary axis, thus, selection and inclusion of people with sexual problems in future studies could be promising. Blaicher (1999) showed that serum concentrations of oxytocin are increased dramatically a minute after orgasm, and that oxytocin surge reached its threshold after five minutes. However, various factors affect women's sexual function and sexual desire [11]. ...
... Blaicher (1999) showed that serum concentrations of oxytocin are increased dramatically a minute after orgasm, and that oxytocin surge reached its threshold after five minutes. However, various factors affect women's sexual function and sexual desire [11]. One factor is the role of women's menstrual cycle [45]. ...
Background Intranasal oxytocin can be used as a promising moiety for the treatment of sexual disorders. Objective This study was carried out to systematically review the effect of intranasal oxytocin on sexual function in men and women. Methods We systematically searched databases (e.g., Cochrane Central Register of Controlled Trials Library, MEDLINE, Web of Science, Scopus, ProQuest, Google Scholar and Persian databases). All types of published clinical trials comparing different doses of intranasal oxytocin sprays with placebo sprays were included in the study. The primary outcome was sexual function and secondary outcomes were endocrine and cardiovascular measures and also side effects. Results A total of six studies were ultimately eligible for inclusion in the study. Though intranasal oxytocin improves various parameters of sexual function in men and women, according to the sexual response cycle, these changes are not statistically meaningful compared to the control group. Only one study revealed a meaningful impact on orgasm parameters and after orgasm, especially in men. In all studies, intranasal oxytocin administration has significantly and transiently increased plasma concentrations of oxytocin with no meaningful effect on other endocrine hormones. A study showed that the heartbeat is increased transiently during the arousal and orgasm stages, and such increase is meaningfully higher in men than in women. Conclusion Intranasal oxytocin administration fails to meaningfully affect the classical parameters of sexual response, but it improves the orgasmic and post-orgasmic dimensions, especially in men. To evaluate the effects of intranasal oxytocin administrations, we need more long-term clinical trials.
... Therefore, it may be worth considering whether in some instances, an absence of sexual intercourse may contribute to a short luteal phase, luteal phase defect, fewer days of peak-type mucus or premenstrual spotting. Like other investigators, we found a substantial variability of the luteal phase length overall (Blaicher et al., 1999;Duijkers et al., 2005;Jones and Lopez, 2006;Fritz and Speroff, 2011). Cycles with fewer days of peak-type mucus have lower potential fecundability (Stanford et al., 2003;Bigelow et al., 2004). ...
... Still, clitoral stimulation and female orgasm may have some residual influence on ovulation timing in humans (Pavli cev and Wagner, 2016). In a recent small study of 11 healthy women, using neuro-imaging technics, researchers showed that compared to a resting state, orgasm increases blood supply and elevates pituitary activation, which leads to higher plasma concentrations of oxytocin and prolactin (Blaicher et al., 1999), which may facilitate ovulation and enhance sperm and oocyte transport (Huynh et al., 2013). ...
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STUDY QUESTION Does sexual intercourse enhance the cycle fecundability in women without known subfertility? SUMMARY ANSWER Sexual intercourse (regardless of timing during the cycle) was associated with cycle characteristics suggesting higher fecundability, including longer luteal phase, less premenstrual spotting and more than 2 days of cervical fluid with estrogen-stimulated qualities. WHAT IS KNOWN ALREADY Human females are spontaneous ovulators, experiencing an LH surge and ovulation cyclically, independent of copulation. Natural conception requires intercourse to occur during the fertile window of a woman’s menstrual cycle, i.e. the 6-day interval ending on the day of ovulation. However, most women with normal fecundity do not ovulate on Day 14, thus the timing of the hypothetical fertile window varies within and between women. This variability is influenced by age and parity and other known or unknown elements. While the impact of sexual intercourse around the time of implantation on the probability of achieving a pregnancy has been discussed by some researchers, there are limited data regarding how sexual intercourse may influence ovulation occurrence and menstrual cycle characteristics in humans. STUDY DESIGN, SIZE, DURATION This study is a pooled analysis of three cohorts of women, enrolled at Creighton Model FertilityCare centers in the USA and Canada: ‘Creighton Model MultiCenter Fecundability Study’ (CMFS: retrospective cohort, 1990–1996), ‘Time to Pregnancy in Normal Fertility’ (TTP: randomized trial, 2003–2006) and ‘Creighton Model Effectiveness, Intentions, and Behaviors Assessment’ (CEIBA: prospective cohort, 2009–2013). We evaluated cycle phase lengths, bleeding and cervical mucus patterns and estimated the fertile window in 2564 cycles of 530 women, followed for up to 1 year. PARTICIPANTS/MATERIALS, SETTING, METHODS Participants were US or Canadian women aged 18–40 and not pregnant, who were heterosexually active, without known subfertility and not taking exogenous hormones. Most of the women were intending to avoid pregnancy at the start of follow-up. Women recorded daily vaginal bleeding, mucus discharge and sexual intercourse using a standardized protocol and recording system for up to 1 year, yielding 2564 cycles available for analysis. The peak day of mucus discharge (generally the last day of cervical fluid with estrogen-stimulated qualities of being clear, stretchy or slippery) was used to identify the estimated day of ovulation, which we considered the last day of the follicular phase in ovulatory cycles. We used linear mixed models to assess continuous cycle parameters including cycle, menses and cycle phase lengths, and generalized linear models using Poisson regression with robust variance to assess dichotomous outcomes such as ovulatory function, short luteal phases and presence or absence of follicular or luteal bleeding. Cycles were stratified by the presence or absence of any sexual intercourse, while adjusting for women’s parity, age, recent oral contraceptive use and breast feeding. MAIN RESULTS AND THE ROLE OF CHANCE Most women were <30 years of age (75.5%; median 27, interquartile range 24–29), non-Hispanic white (88.1%), with high socioeconomic indicators and nulliparous (70.9%). Cycles with no sexual intercourse compared to cycles with at least 1 day of sexual intercourse were shorter (29.1 days (95% CI 27.6, 30.7) versus 30.1 days (95% CI 28.7, 31.4)), had shorter luteal phases (10.8 days (95% CI 10.2, 11.5) versus 11.4 days (95% CI 10.9, 12.0)), had a higher probability of luteal phase deficiency (<10 days; adjusted probability ratio (PR) 1.31 (95% CI 1.00, 1.71)), had a higher probability of 2 days of premenstrual spotting (adjusted PR 2.15 (95% CI 1.09, 4.24)) and a higher probability of having two or fewer days of peak-type (estrogenic) cervical fluid (adjusted PR 1.49 (95% CI 1.03, 2.15)). LIMITATIONS, REASONS FOR CAUTION Our study participants were geographically dispersed but relatively homogeneous in regard to race, ethnicity, income and educational levels, and all had male partners, which may limit the generalizability of the findings. We cannot exclude the possibility of undetected subfertility or related gynecologic disorders among some of the women, such as undetected endometriosis or polycystic ovary syndrome, which would impact the generalizability of our findings. Acute illness or stressful events might have reduced the likelihood of any intercourse during a cycle, while also altering cycle characteristics. Some cycles in the no intercourse group may have actually had undocumented intercourse or other sexual activity, but this would bias our results toward the null. The Creighton Model FertilityCare System (CrM) discourages use of barrier methods, so we believe that most instances of intercourse involved exposure to semen; however, condoms may have been used in some cycles. Our dataset lacks any information about the occurrence of female orgasm, precluding our ability to evaluate the independent or combined impact of female orgasm on cycle characteristics. WIDER IMPLICATIONS OF THE FINDINGS Sexual activity may change reproductive hormonal patterns, and/or levels of reproductive hormones may influence the likelihood of sexual activity. Future work may help with understanding the extent to which exposure to seminal fluid, and/or female orgasm and/or timing of intercourse could impact menstrual cycle function. In theory, large data sets from women using menstrual and fertility tracking apps could be informative if women can be appropriately incentivized to record intercourse completely. It is also of interest to understand how cycle characteristics may differ in women with gynecological problems or subfertility. STUDY FUNDING/COMPETING INTEREST(S) Funding for the research on the three cohorts analyzed in this study was provided by the Robert Wood Johnson Foundation #029258 (Creighton Model MultiCenter Fecundability Study), the Eunice Kennedy Shriver National Institute of Child Health and Human Development 1K23 HD0147901-01A1 (Time to Pregnancy in Normal Fertility) and the Office of Family Planning, Office of Population Affairs, Health and Human Services 1FPRPA006035 (Creighton Model Effectiveness, Intentions, and Behaviors Assessment). The authors declare that they have no conflict of interest. TRIAL REGISTRATION NUMBER N/A.
... Plasma OXT levels can be supremely correlated with towering levels of arousal and lubrication, as measured by the Female Sexual Function Index (Salonia et al., 2005). Plasma OXT levels rise in females during sexual arousal and are raised further by orgasm (Blaicher et al., 1999;Carmichael et al., 1987). ...
This chapter is about the physiological changes and chemical changes occuring in the human brain during the conditions of love and affection.
... For instance, if a couple is separated for a long period of time, anxiety can increase due to the lack of physical affection. Oxytocin may assist romantically attached couples by lessening their emotions of anxiety when they are separated [59]. Sex is one of our biggest obsessions-causing thrills, anguish and downright confusion. ...
... Although some studies have reported that OT concentrations are increased in both sexes during sexual orgasm (Blaicher et al., 1999) or in response to social touch , and may act synergistically with estrogen (Amico et al., 1981;Young et al., 1998;Patisaul et al., 2003;Salonia et al., 2005), there is still no compelling evidence that OT actually increases sexual desire in women and potentially the increased release following orgasm or in response to touch may function primarily to strengthen bonds between partners. Indeed, the study showing that OT facilitated social sharing behaviors in pair-bonded marmosets found no evidence that it increased female sexual behavior (Smith et al., 2010). ...
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In humans, the neuropeptide oxytocin promotes both attraction toward and bonds with romantic partners, although no studies have investigated whether this extends to the perceived attractiveness of flirtatious language. In a within-subject, randomized double-blind placebo-controlled behavior and functional magnetic resonance imaging (fMRI) paradigm ( ), 75 women rated the attractiveness of either a male face alone or paired with a verbal compliment which varied in terms of topic (women or landscapes) and figurativeness (novel or conventional metaphors or literal expressions). Subjects were tested in fertile and luteal phases of their cycle and on both occasions received either 24 IU intranasal oxytocin or placebo. Results showed that, whereas under placebo women in the fertile phase rated the facial attractiveness of men producing novel metaphorical compliments higher than in their luteal phase, following oxytocin treatment they did not. Correspondingly, under oxytocin the faces of individuals producing novel metaphorical compliments evoked greater responses in brain regions involved in processing language (middle frontal gyrus) and cognitive and emotional conflict (posterior middle cingulate and dorsal anterior cingulate) but reduced functional connectivity between the dorsal anterior cingulate and right orbitofrontal and medial frontal gyri. Thus, sex hormones and oxytocin may have opposite effects in regulating mate selection in women during their fertile phase. Novel metaphorical compliments convey a greater sexual than bonding intention and thus while sex hormones at mid-cycle may promote attraction to individuals communicating sexual rather than bonding intent, oxytocin may bias attraction away from such individuals through increasing cognitive and emotional conflict responses toward them.
This chapter first reviews theories that have suggested that a large part of sexual offenders, problems are attachment issues, particularly Marshall's work (which is outlined in Chapter 1). We then outline the background to Ward and Beech's theory of sexual offending (updated in Chapter 6). We subsequently consider how disturbances in the neurobiological/neurochemical processes at a young age lead to these problematic attachment styles in later life, and which can potentiate the probability of sexual offending in the light of a preliminary neurological model by Mitchell and Beech.
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Oxytocin is a peptide‐hormone extensively studied for its multifaceted biological functions and has recently gained attention for its role in eating behavior, through its action as an anorexigenic neuropeptide. Moreover, the gut microbiota is involved in oxytocinergic signaling through the brain‐gut axis, specifically in the regulation of social behavior. The gut microbiota is also implicated in appetite regulation and is postulated to play a role in central regulation of hedonic eating. In this review, we provide an overview on oxytocin and its individual links with the microbiome, the homeostatic and non‐homeostatic regulation of eating behavior as well as social behavior and stress. This article is protected by copyright. All rights reserved.
Pregnant women and their partners often ask healthcare professionals whether sex is safe during pregnancy, and what consequences may result from sexual activity. Many clinicians can also be unsure of the answers to these type of questions, leading to both patient and clinician resorting to the internet for advice, which can be inaccurate and anxiety-inducing. Here, the authors provide clinicians with an insight into the information offered by 'Dr Google' so that they can reassure and advise their patients as necessary. Aimed at obstetricians and other physicians caring for pregnant women, this book reviews the implications of sex during pregnancy such as those complicated by medical conditions, those at risk of preterm birth and multiple pregnancies. Other chapters cover physiological changes during pregnancy that may affect sexual function and intimacy, as well as the differing guidelines provided by various global obstetric societies.
Current evidence suggests that oestrogens, progesterone, relaxin, the prostaglandins, and oxytocin are all hormones concerned to a major degree with the onset and maintenance of parturition. Oestrogens, relaxin, and the prostaglandins are particularly involved with cervical ripening, while prostaglandins, progesterone and oxytocin are more involved in regulating myometrial contractility. Catecholamines may also have some regulatory function in relation to uterine contractions. Progesterone dominance during pregnancy is associated with a firm closed cervix, few myometrial gap junctions, low calcium levels in the cells, and a quiescent myometrium. At term, a change in the oestrogen/progesterone balance favours cervical ripening and increased uterine activity. Of particular importance at the level of the muscle cell are changes in the number of oxytocin receptors; a complex interaction between cAMP and phosphoinositide metabolism governs the intracellular level of calcium, thus regulating contractile activity.
The neuropeptide oxytocin, synthetized by magnocellular neurons in the hypothalamus, is well known for its peripheral action after it is released into the bloodstream from axons in the neurohypophysis. Less familiar is the notion that it is also released centrally to control the activity of oxytocinergic neurons themselves. When injected into the third ventricle of lactating rats during suckling, oxytocin increases the basal firing rate of oxytocinergic neurons as well as their activity at the time of each reflex milk ejection. On the other hand, centrally administered oxytocin engenders the neuronal-glial and synaptic plasticity characteristic of the oxytocin system when it is physiologically activated. From numerous in vivo and in vitro observations, it appears that central oxytocin is released in the hypothalamic nuclei themselves. For example, the use of push-pull cannulae inserted into one supraoptic nucleus of suckled rats shows that oxytocin is released inside the nucleus specifically during milk ejection. Moreover, ultrastructural immunocytochemistry reveals synaptic terminals in the supraoptic nucleus where both the pre- and postsynaptic elements are oxytocinergic. Nevertheless, the mechanism of the central release of the neuropeptide has still to be determined, especially in view of electrophysiological observations indicating that the release process in the hypothalamus is different from that within the neurohypophysis.
Neurons of the ventromedial hypothalamus (VMH) in female rats were electrophysiologically recorded via multibarrelled glass micropipettes and tested for responsiveness to vaginocervical stimulation as well as to a variety of other peripheral stimuli. A small percentage of VMH neurons were found to be specifically responsive to vaginocervical stimulation (type I response) in the ovariectomized animal. Priming the rats with estrogen (E) and progesterone (P) significantly increased the percentage of neurons responding specifically to vaginocervical stimulation but had no effect on the percentage of nonspecifically responding (type II) and nonresponding (type III) neurons. Pharmacological testing of all three types of VMH neurons was accomplished by iontophoretic application of luteinizing hormone releasing hormone (LHRH), prolactin (PRL), and dopamine (DA) to the cell membrane. PRL excited the majority of neurons tested and DA inhibited the majority of tested units regardless of the hormonal condition of the animal or the response elicited by vaginocervical and peripheral stimulation, LHRH, however, produced changes in firing rate which were related to the type of response evoked by vaginocervical stimulation. In E-P-primed animals, neurons which were specifically or nonspecifically affected by vaginocervical stimulation responded to LHRH in a similar manner whereas a different LHRH response profile was obtained in those neurons which were not effected by vaginocervical stimulation. The results indicate that an afferent pathway from the vaginocervix to the VMH exists, that E-P priming in some manner increases the probability that a VMH neuron will respond specifically to vaginocervical probing, and that the effect of LHRH is different in neurons responding to vaginocervical stimulation than in nonresponding neurons.
A positive correlation was observed between the midcycle elevation of estrogen (E) and the level of oxytocin- and estrogen-stimulated neurophysin (ESN), the protein carrier of oxytocin, in the plasma of five of six women. The time of the maximal level of E was associated with a level of oxytocin significantly greater than that in either the early follicular or late luteal phase (P less than 0.025). Likewise, the level of ESN at midcycle was greater than the level of ESN in the early follicular or late luteal phase (P less than 0.01). Other than states of lactation or pregnancy, this is the only described cyclic secretion of oxytocin in humans. Since oxytocin chronologically correlates with a rise in the level of E at midcycle, a role for oxytocin in ovulation may be considered.
This study assesses the influence of menstrual cycle phases and hormones on female sexual interest in both a nonclinical sample of volunteers (n = 18) and women who complained of premenstrual tension (n = 150). Women were assessed prospectively for two menstrual cycles with daily symptom charts. In addition mental status was assessed clinically and the Moos Menstrual Distress Questionnaire completed in the follicular and premenstrual phases. On the basis of these assessments women were assigned to subject groups. During the second cycle, daily 24-h urinary estrogens and urinary pregnanediol were determined. Sexual interest and feelings of well-being were recorded on a daily symptom rating chart. Sexual interest was found to be significantly higher in the follicular and ovulatory phases, than in the luteal, premenstrual, or menstrual phases. Sexual interest and feelings of well-being were correlated (R = 0.29). Sexual interest and feelings of well-being were not correlated with urinary estrogen or pregnanediol levels.
The presence of biologically active nerve growth factor (NGF) in the peripheral circulation of women during pregnancy, labour and lactation was investigated. Using a sensitive immunoenzymatic assay (ELISA), we found an approximately five-fold increase in plasma NGF levels during labour and lactation compared with the concentrations found at the term of gestation or in control healthy women. Since labour and lactation are characterized by activation of the hypothalamo-pituitary-adrenal axis and by high plasma levels of the neurohypophyseal hormone oxytocin, and since the intravenous injection of oxytocin in female rats causes a 176% increase in the hypothalamic levels of NGF, it is possible that the increased amount of circulating NGF is correlated with one or both of these events.
A search of the literature has been prepared to determine how oxytocin may affect sexual and reproductive in women. Many animal studies suggest that oxytocin induces a variety of reproductive behaviors, including grooming, sexual arousal, orgasm, gamete transport, nesting, birthing, and specific maternal behaviors such as breast-feeding and bonding between mother and infant. These actions are apparently facilitated by the 'priming' effect on certain cells by sex and steroid hormones - as the brief case report would also suggest. However, no adequate double-blind trial has confirmed the observations from this report in women. Only animal studies have been performed, albeit over a wide range of species. A variety of other causes and effects of sexual interest and arousal relating to oxytocin are considered, including some of those in males. More research is needed to clarify the role of oxytocin in human reproductive behaviors, including its potential 'aphrodisiac' or prosexual effect in women in the presence of the sex-steroid hormones.