The role of oxytocin in relation to female sexual arousal

Microbes, oxytocin and stress: Converging players regulating eating behavior

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.

Characteristics of menstrual cycles with or without intercourse in women with no known subfertility

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 INTERESTS

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.

Oxytocin Reduces the Attractiveness of Silver-Tongued Men for Women During Mid-Cycle

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 (https://clinicaltrials.gov/show/NCT03144115), 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.

Endogenous oxytocin, cortisol, and testosterone in response to group singing

Humans have sung together for thousands of years. Today, regular participation in group singing is associated with benefits across psychological and biological dimensions of human health. Here we examine the hypothesis that a portion of these benefits stem from changes in endocrine activity associated with affiliation and social bonding. Working with a young adult choir (n = 71), we measured changes salivary concentrations of oxytocin, cortisol, and testosterone from before and after four experimental conditions crossing two factors: vocal production mode (singing vs. speaking) and social context (together vs. alone). Salivary oxytocin and cortisol decreased from before to after the experimental manipulations. For oxytocin the magnitude of this decrease was significantly smaller after singing compared to speaking, resulting in concentrations that were significantly elevated after singing together compared to speaking together, after controlling for baseline differences. In contrast, the magnitude of the salivary cortisol decreases was the same across experimental manipulations, and although large, could not be separated from diurnal cycling. No significant effects were found in a low-powered exploratory evaluation of testosterone (tested only in males). At a psychological level, we found that singing stimulates greater positive shifts in self-perceived affect compared to speaking-particularly when performed together-and that singing together enhances feelings of social connection more than speaking together. Finally, measurements of heart rate made for a subset of participants provide preliminary evidence regarding physical exertion levels across conditions. These results are discussed in the context of a growing multidisciplinary literature on the endocrinological correlates of musical behavior. We conclude that singing together can have biological and psychological effects associated with affiliation and social bonding, and that these effects extend beyond comparable but non-musical group activities. However, we also note that these effects appear heavily influenced by broader contextual factors that shape social dynamics, such as stress levels, the intimacy of interactions, and the status of existing relationships.

The effect of baculum shape and mating behavior on mating-induced prolactin release in female house mice

Male genitalia are subject to rapid divergent evolution, and sexual selection is believed to be responsible for this pattern of evolutionary divergence. Genital stimulation during copulation is an essential feature of sexual reproduction. In mammals, the male intromittent genitalia induces a cascade of physiological and neurological changes in females that promote pregnancy. Previous studies of the house mouse have shown that the shape of the baculum (penis bone) influences male reproductive success and responds to experimentally imposed variation in sexual selection. Here, we test the hypothesis that the baculum is subject to sexual selection due to a stimulatory function during copulation. We selected male and female house mice (Mus musculus domesticus) from families with breeding values at the extremes of baculum shape and performed two series of experimental matings following which we examined the concentration of prolactin in the blood of females either 15 (“early”) or 75 (“late”) min after ejaculation. Our results provide evidence of a mating-induced release of prolactin in the female house mouse early after ejaculation, the level of which is dependent on an interaction between the shape of the baculum and male sexual behavior. Our data thereby provide novel insight into the mechanism(s) of sexual selection acting on the mammalian baculum.

Effects of Sleep Deprivation by Olfactorily Induced Sexual Arousal Compared to Immobilization Stress and Manual Sleep Deprivation on Neuromessengers and Time Keeping Genes in the Suprachiasmatic Nuclei and Other Cerebral Entities of Syrian Hamsters-An Immunohistochemical Study

We investigated the effects of sexual arousal induced by olfactory stimuli on the expression of neuromodulators, neurotransmitters and sexual steroid receptors in the suprachiasmatic nucleus (SCN, the circadian pacemaker of mammals) and other cerebral entities of Syrian hamsters (Mesocricetus auratus) compared to manual sleep deprivation and immobilization stress. The hamsters kept under a 12:12 hours (h) light:dark cycle were deprived of sleep by sexual stimulation, gentle manual handling or immobilization stress for 1 h at the beginning of the light phase and subsequently sacrificed at zeitgeber time 01:00, respectively; for comparison, hamsters were manually sleep deprived for 6 or 20 h or sacrificed after completing a full sleep phase. As demonstrated by immunohistochemistry, apart from various alterations after manual sleep deprivation, sexual stimulation caused down-regulation of arginine-vasopressin (AVP), vasointestinal peptide (VIP), serotonin (5-HT), substance P (SP), and met-enkephalin (ME) in the SCN. Somatostatin (SOM) was diminished in the medial periventricular nucleus (MPVN). In contrast, an increase in AVP was observed in the PVN, that of oxytocin (OXY) in the supraoptic nucleus (SON), of tyrosine-hydroxylase (TH) in the infundibular nucleus (IN), and dopamine beta-hydroxylase (DBH) in the A7 neuron population of the brain stem (A7), respectively. Testosterone in plasma was increased. The results indicate that sexual arousal extensively influences the neuropeptide systems of the SCN, suggesting an involvement of the SCN in reproductive behavior.

Female Sexual Dysfunction in Primary Adrenal Insufficiency

Purpose. No data are currently available on female sexual dysfunction (FSD) in primary adrenal insufficiency (PAI) and the possible impact of replacement therapy. The aim of this study was to evaluate the prevalence of FSD and sexual distress (SD), and to evaluate the possible impact of replacement therapy on sexuality in women with PAI. Methods. Female Sexual Function Index-6 (FSFI-6) and Sexual Distress Scale (SDS) questionnaires were administered to 22 women with PAI and 23 healthy women matched for age as controls. Results. The prevalence of sexual symptoms measured by FSFI-6 (total score < 19) was significantly higher in women with PAI (15/22; 68.2%) compared to the controls (2/23; 8.7%; p = 0.001). Regarding the questionnaire items, significantly different scores were found for desire (p < 0.001), arousal (p = 0.0006), lubrication (p = 0.046) and overall sexual satisfaction (p < 0.0001) in women with PAI compared to the controls. The rate of FSD (FSFI < 19 with SDS >15) was 60% in patients with PAI. A significant inverse correlation was found between FSFI-6 total scores and SD (r = −0.65; p = 0.0011), while a significant direct correlation was found between FSFI-6 total scores and serum cortisol levels (r = 0.55; p = 0.035). Conclusions. A higher prevalence of FSD was found in women affected by PAI compared to healthy women. Desire seems to be the most impaired aspect of sexual function. Moreover, sexual dysfunction in this population seems to be related to sexual distress and cortisol levels.

How Relevant is the Systemic Oxytocin Concentration for Human Sexual Behavior? A Systematic Review

Introduction

Despite its role in social cognition and affiliative behavior, less is known about the role played by oxytocin in human sexual behavior.

Aim

In the present systematic review, we aimed to find the levels of oxytocin related to human sexual arousal and orgasm.

Methods

We conducted the study according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We performed a systematic search in the principal databases for studies that reported collection of salivary or plasmatic samples, with dosage of oxytocin in relation to sexual activity during induction of sexual arousal and orgasm.

Results

414 articles were obtained. After duplicates removal and the application of pre exclusion criteria, 16 articles were considered eligible and 13 articles were included with a Cohen's k of 0.827. Most of the studies used sexual self-stimulation and collected plasmatic or salivary samples to measure oxytocin. The sexual arousal and orgasm were assessed based on subjective reports.

Main Outcome Measure

The primary outcomes were the oxytocin levels collected during the induction of sexual arousal and orgasm.

Conclusions

Several studies collected only subjective reports about the sexual arousal and the orgasm. Most of the studies found higher levels of oxytocin during the orgasm or ejaculation. Given the sexual arousal evoked by self-stimulation in which sexual fantasies play an important role, it should be possible to postulate for a role of the oxytocin in sexual desire. In particular, we hypothesize a complex role of the oxytocin in the modulation of sexual fantasies and thoughts that are relevant in the sexual desire and help to trigger genital and sexual arousal.

Cera N, Vargas-Cáceres S, Oliveira C, et al. How Relevant is the Systemic Oxytocin Concentration for Human Sexual Behavior? A Systematic Review. Sex Med 2021;9:100370.

Women's Cortisol Stress Responsivity, Sexual Arousability, and Sexual History

Life history theory and the adaptive calibration model state that characteristics of one's early environment influence individual differences in both neuroendocrine reactivity to stress and sexual risk-taking behavior. However, few studies have directly examined the relationship between neuroendocrine reactivity to stress and risky sexual behavior. This study used multilevel modeling to test whether cortisol reactivity and recovery in response to laboratory stress were associated with women's history of sexual behavior and their sexual arousability in response to laboratory sexual stimuli. Participants were 65 women (35% heterosexual, 44% bisexual, and 21% lesbian) who completed two laboratory sessions, two weeks apart. Women's self-reported sexual arousability to sexual stimuli interacted with their sexual abuse history to predict their trajectories of cortisol stress reactivity and recovery. Cortisol reactivity and recovery were not associated with women's sexual risk taking, such as the age of sexual debut, sociosexuality, or lifetime number of sexual partners.

The effect of oxytocin vaginal gel on vaginal atrophy in postmenopausal women: a randomized controlled trial

Background

Around 90% of postmenopausal women are suffering from vaginal atrophy. This study aimed to evaluate the effect of oxytocin vaginal gel on vaginal atrophy among postmenopausal women.

Methods

This was a randomized controlled trial that was conducted on 96 postmenopausal women who suffered from vaginal atrophy. The inclusion criteria were: literate women, age 40–60, at least 1 year passed from their last menstrual period or the level of FSH > 40 IU, monogamous women with the sexual relationship. Women in the intervention group, requested to use one applicator of 400 IU oxytocin gel per night and women in the placebo group used placebo each night. The subjective symptoms of vaginal atrophy, vaginal PH, maturation index were measured before and after the intervention.

Results

The number of superficial cells was increased significantly in the oxytocin group compared to placebo (38.7 ± 7.18 vs. 3.69 ± 2.76, p = 0.0001), while the number of parabasal cells was decreased significantly in the oxytocin compared to placebo after the intervention. The improvement of the maturation index was more dominant in the oxytocin group (increased from 7.76 ± 4.68 to 52.48 ± 7.54) in comparison to the placebo group (increased from 8.58 ± 4.35 to 13.25 ± 5.06). The PH of the vagina decreased significantly in the oxytocin group in comparison to the placebo group (p = 0.0001). After 8 weeks, 88.6 and 7.1% of women in the oxytocin and placebo groups did not show the severe symptoms of vaginal atrophy (p = 0.001).

Conclusion

The results of this study showed that eight- week intervention with oxytocin vaginal gel (400 IU) could significantly improve the vaginal maturation index, subjective symptoms of vaginal atrophy and reduce the PH of the vagina. Using this medication in women who have a contraindication for hormone therapy is recommended.

Trial registration

IRCT20160602028220N2.

Interactions between inflammation and female sexual desire and arousal function

PURPOSE OF REVIEW

To describe the current state of research on interactions between inflammation and female sexual function.

RECENT FINDINGS

Inflammation may interfere with female sexual desire and arousal via direct (neural) and indirect (endocrine, vascular, social/behavioral) pathways. There are significant sex differences in the effect of inflammation on sexual function, arising from different evolutionary selection pressures on regulation of reproduction. A variety of inflammation-related conditions are associated with risk of female sexual dysfunction, including cardiovascular disease, metabolic syndrome, and chronic pain.

SUMMARY

Clinical implications include the need for routine assessment for sexual dysfunction in patients with inflammation-related conditions, the potential for anti-inflammatory diets to improve sexual desire and arousal function, and consideration of chronic inflammation as moderator of sexual effects of hormonal treatments. Although the evidence points to a role for inflammation in the development and maintenance of female sexual dysfunction, the precise nature of these associations remains unclear.

Romantic Love and Reproductive Hormones in Women

Increased reproductive success is among the most commonly proposed adaptive functions of romantic love. Here, we tested if hormonal changes associated with falling in love may co-vary with hormonal profiles that predict increased fecundity in women. We compared blood serum levels of estradiol (E2, E2/T), luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), free testosterone (fT), and cortisol (CT), measured in the early follicular phase of the menstrual cycle in single women (N = 69) and in women at the beginning of a romantic heterosexual relationship who reported being in love with their partner (N = 47). Participants were healthy, regularly cycling women aged 24 to 33 who did not use hormonal contraception. We found that women in love had higher levels of gonadotropins (FSH, LH) and lower testosterone levels compared to single women who were not in love. These groups of women did not, however, differ in terms of estradiol, prolactin, or cortisol levels.

Associations between oxytocin and cortisol reactivity and recovery in response to psychological stress and sexual arousal

Previous research suggests a dynamic regulatory relationship between oxytocin and cortisol, but the specific nature of this relationship and its context-specificity have not been fully specified. In the present study, we repeatedly assessed both salivary oxytocin and salivary cortisol during two experimental sessions (one inducing sexual arousal and one inducing psychological stress), conducted two weeks apart with the same group of 63 female participants. Baseline cortisol and baseline oxytocin were significantly correlated in both sessions. Cortisol levels showed significantly different patterns of change during the stress assessment than during the sexual arousal assessment, but oxytocin showed similar patterns of change across both assessments. Greater cortisol stress reactivity predicted higher oxytocin levels immediately after the stressor, but a different pattern emerged during the arousal assessment: Greater oxytocin arousal reactivity predicted attenuated post-arousal reductions in cortisol. For both cortisol and oxytocin, individual differences in women's reactivity to sexual arousal did not predict their reactivity to psychological stress. These findings contribute new insights regarding associations between cortisol and oxytocin reactivity and recovery in different psychological contexts.

The 'Pleasure&Pregnancy' web-based interactive educational programme versus expectant management in the treatment of unexplained subfertility: protocol for a randomised controlled trial

INTRODUCTION

Many subfertile couples are diagnosed with (relatively) unexplained subfertility and a good prognosis. National professional guidelines (eg, the Netherlands and UK) advise 'expectant management (EM)' for 6-12 months, in which no interaction with healthcare staff is offered. Underpowered studies indicate that face-to-face sex-counselling increases the ongoing pregnancy rates of these couples. In patients with other conditions, web-based interactive educational programmes have the same effect on sexual functioning as face-to-face sex counselling. The 'Pleasure&Pregnancy randomised controlled trial (RCT)' will examine in couples with unexplained subfertility and a good prognosis whether a new web-based interactive educational programme results in a higher chance of naturally conceiving an ongoing pregnancy within 6 months as compared with EM.

METHODS AND ANALYSIS

A multicentre RCT with cost-effectiveness analysis will include heterosexual couples diagnosed with (relatively) unexplained subfertility and a good prognosis in Dutch and Belgian secondary or tertiary fertility clinics. Couples will be randomised between 6 months of EM and 6 months of the Pleasure&Pregnancy-programme. This new web-based interactive educational programme includes eight progressive modules of information (on the biology of conception and pleasurable sex) and sensate focus, couple communication and mindfulness exercises. Couples are offered interaction with their coaches via email and can take part in three moderated chat sessions with peers. The primary outcome of this RCT is the probability of naturally conceiving an ongoing pregnancy within 6 months after randomisation. Secondary outcomes include time-to-pregnancy, live birth rate, costs, sexual functioning and personal and relational well-being. Analysis will be according to intention to treat.

ETHICS AND DISSEMINATION

This study has been approved by the Medical Ethical Committees of the Academic Medical Centre (the Netherlands) and the Leuven University Hospital (Belgium). The findings of this RCT will be disseminated through presentations at international scientific meetings and peer-reviewed publications.

TRAIL REGISTRATION NUMBER

NTR5709; Pre-results.

Subjective and Oxytocinergic Responses to Mindfulness Are Associated With Subjective and Oxytocinergic Responses to Sexual Arousal

Mindfulness – the ability to pay attention, on purpose, without judgment, and in the present moment – has consistently been shown to enhance women’s sexual arousal. As a first step toward understanding potential neuroendocrine underpinnings of mindfulness and sexual arousal, we examined whether individual differences in subjective and neuroendocrine (i.e., oxytocin) responses to mindful breathing were associated with individual differences in subjective and neuroendocrine responses to sexual arousal. To achieve this aim, 61 lesbian, bisexual, and heterosexual women completed a questionnaire assessing dispositional mindfulness, underwent an arousal task while continuously rating their sexual arousal and a mindful breathing task, after which participants reported on their ability to detect attentional shifts, and provided salivary samples after each assessment. Results indicated that women who were quicker to detect attentional shifts and women who reported greater sexual arousability reported larger changes (decreases) in oxytocin in response to mindful breathing and were the only women to report increases in oxytocin in response to the sexual arousal induction. Results further indicated that individuals who report greater subjective responsiveness to mindfulness and sexual arousal appear to have an oxytocinergic system that is also more responsive to both arousal and to mindfulness. These results make a significant contribution to our understanding of the role of attentional processes in sexual arousal, and warrant future examination of oxytocin as a potential neuroendocrine mechanism underlying the link between mindfulness and sexual arousal.

Oxytocin increases eye-gaze towards novel social and non-social stimuli

Research on oxytocin (OT) has revealed a substantial involvement of this neuropeptide in social cognition processes and attachment behavior. The rationale of the present project was to decipher the differential role of OT in basic social cognition processes towards non-erotic attachment stimuli vs. reproduction-related stimuli in human subjects. In a randomized double-blind repeated-measures cross-over design, N = 82 participants were investigated twice and received either intranasal OT or placebo at the first assessment followed by placebo or OT at second assessment. Participants were presented with standardized pictures of parent-child dyads, romantic couples engaging in non-erotic or explicit sexual activities, and non-social pictures while we assessed pupil dilation and eye focus on specific pre-defined areas of interest. Multilevel analyses suggest that during the initial presentation, OT increased pupil dilation towards all categories of stimuli and led the eye focus towards the eyes and body regions, followed by a strong decrease in pupil dilation and fixations at the second session. These carry-over effects indicate that hormonal treatment at an initial contact to social stimuli can determine how these stimuli are processed later. These results might have implications for OT as a treatment in interventions with repeated exposure to social material.

Sexual Activity and Cognitive Decline in Older Adults

This prospective study tested whether sexual activity and emotional closeness during partnered sexual activity relate to cognitive decline (episodic memory performance) in older adulthood. In total, 6016 adults aged 50 and over (2672 men, 3344 women; M age = 66.0 ± 8.8 years) completed an episodic memory task and self-report questions related to health, sexual activity, and emotional closeness. Two years later, participants again completed the episodic memory task. After controlling for demographic and health-related lifestyle factors, more frequent sexual activity and greater emotional closeness during partnered sexual activity were associated with better memory performance. The association between sexual activity and memory performance was stronger among older participants in the sample. Memory performance worsened over 2 years, but change in memory performance was unrelated to sexual activity or emotional closeness during partnered sexual activity. These findings build on experimental research that has found sexual activity enhances episodic memory in non-human animals. Further research using longer timeframes and alternative measures of cognitive decline is recommended.

The Oxytocin Receptor: From Intracellular Signaling to Behavior

The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1 , as listed in PubMed), which revealed central roles for OXT and its receptor (OXTR) in reproduction, and social and emotional behaviors in animal and human studies focusing on mental and physical health and disease. In this review, we discuss the mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OXTR-coupled signaling cascades, and their involvement in behavioral outcomes to assemble a comprehensive picture of the central and peripheral OXT system. Traditionally known for its role in milk let-down and uterine contraction during labor, OXT also has implications in physiological, and also behavioral, aspects of reproduction, such as sexual and maternal behaviors and pair bonding, but also anxiety, trust, sociability, food intake, or even drug abuse. The many facets of OXT are, on a molecular basis, brought about by a single receptor. The OXTR, a 7-transmembrane G protein-coupled receptor capable of binding to either Gαior Gαqproteins, activates a set of signaling cascades, such as the MAPK, PKC, PLC, or CaMK pathways, which converge on transcription factors like CREB or MEF-2. The cellular response to OXT includes regulation of neurite outgrowth, cellular viability, and increased survival. OXTergic projections in the brain represent anxiety and stress-regulating circuits connecting the paraventricular nucleus of the hypothalamus, amygdala, bed nucleus of the stria terminalis, or the medial prefrontal cortex. Which OXT-induced patterns finally alter the behavior of an animal or a human being is still poorly understood, and studying those OXTR-coupled signaling cascades is one initial step toward a better understanding of the molecular background of those behavioral effects.

Effects of Intranasal Oxytocin Administration on Sexual Functions in Healthy Women: A Laboratory Paradigm

PURPOSE

The neuropeptide oxytocin (OXT) has a variety of physiological functions in maternal behavior and attachment including sexual behavior. Based on animal research and our previous human studies, we set out to investigate intranasal administration of OXT and hypothesized that OXT should be able to modulate sexual function in women.

METHODS

In a double-blind, placebo-controlled, crossover laboratory setting, the acute effects of intranasal administered OXT (24 international units) on sexual drive, arousal, orgasm, and refractory aspects of sexual behavior were analyzed in 27 healthy females (mean age ± SD, 27.52 ± 8.04) together with physiological parameters using vaginal photoplethysmography.

FINDINGS

Oxytocin administration showed no effect on subjective sexual parameters (eg, postorgasmic tension; P = 0.051). Physiological parameters (vaginal photoplethysmography amplitude and vaginal blood volume) showed a response pattern towards sexual arousal but were not affected by OXT.

IMPLICATIONS

Using a well-established laboratory paradigm, we did not find that intranasal OXT influences female sexual parameters. Also, sexual drive and other functions were not affected by OXT. These findings indicate that OXT is not able to significantly increase subjective and objective parameters of sexual function in a setting with high internal validity; however, this might be different in a more naturalistic setting.

Oxytocin plasma levels in orgasmic and anorgasmic women

The study aimed to evaluate oxytocin (Oxt) serum levels before and after sexual intercourse in women affected by anorgasmia. The sample was constituted of 15 anorgasmic women and 16 orgasmic women. The Female Sexual Function Index (FSFI, cutoff ≤26.55) and the Female Sexual Distress Scale (FSDS, cutoff ≥15) questionnaires were used to assess sexual function and sexual distress, respectively. Serum Oxt levels were measured before sexual intercourse (T0) and 5 min after coital sexual activity (T1). Anorgasmic women had an unpleasant sexual experience (FSFI total score, 20.1 ± 1.2;) and were stressed (FSDS score, 19.4 ± 1.3), whereas orgasmic women were fully satisfied with their sexual activity (FSFI total score 28.7 ± 1.3; FSDS score 11.5 ± 1.8). At T0, anorgasmic women had lower levels of Oxt than orgasmic women, 1.8 ± 0.2 pg/mL versus 2.1 ± 0.5 pg/mL, respectively, [95% CI: (-0.58, -0.01); p < .04]. At T1, Oxt levels did not change in anorgasmic women (1.8 ± 0.2 pg/mL versus 2 ± 0.4 pg/mL, p = .09). Finally, orgasmic women had higher levels of Oxt than anorgasmic women, 4.6 ± 0.7 pg/mL versus 2 ± 0.4 pg/mL, respectively [95% CI: (-3.02, -2.17); p < .001]. The repetitive processes to experience the sexual body sensations could represent a survival behavior of species by attachment to a partner.

Endocrinology of human female sexuality, mating, and reproductive behavior

Hormones orchestrate and coordinate human female sexual development, sexuality, and reproduction in relation to three types of phenotypic changes: life history transitions such as puberty and childbirth, responses to contextual factors such as caloric intake and stress, and cyclical patterns such as the ovulatory cycle. Here, we review the endocrinology underlying women's reproductive phenotypes, including sexual orientation and gender identity, mate preferences, competition for mates, sex drive, and maternal behavior. We highlight distinctive aspects of women's sexuality such as the possession of sexual ornaments, relatively cryptic fertile windows, extended sexual behavior across the ovulatory cycle, and a period of midlife reproductive senescence-and we focus on how hormonal mechanisms were shaped by selection to produce adaptive outcomes. We conclude with suggestions for future research to elucidate how hormonal mechanisms subserve women's reproductive phenotypes.

Uterine peristalsis and fertility: current knowledge and future perspectives: a review and meta-analysis

Although uterine contractions in the non-pregnant uterus have been studied extensively, the knowledge gained has not been used in general fertility treatment work-up. In this review paper, we provide an overview of the current knowledge on uterine peristalsis (UP), based on the available literature. This literature shows that UP influences pregnancy chances in both natural and artificial cycles. Although the physiological background of these contractions is not completely clear, we know that several factors can be of influence, like uterine pathologies and hormones. Several options to alter pregnancy outcome by interfering with uterine contractions have been studied. Our meta-analysis on therapeutic options shows positive results of progesterone at time of embryo transfer in IVF cycles or prostaglandins at time of intrauterine insemination, although the quality of evidence is low. These therapies are probably most beneficial in selected groups of patients with abnormal contraction patterns. The introduction of an objective and user-friendly UP measuring tool suitable for use in daily practice would make it possible to identify and monitor these patients. We suggest that future research should focus on the physiology of initiation of UP and on the development of an effective standard measuring tool.

Biomarkers of Inflammation Mediate an Association Between Sexual Activity and Quality of Life in Older Adulthood

BACKGROUND

Inflammatory processes underlie biological mechanisms responsible for age-related disease and quality of life. Psychological stress can activate acute-phase reactants associated with inflammation, and sexual activity can assist in the management of stress.

AIM

To test whether inflammatory biomarkers (C-reactive protein [CRP], fibrinogen, and white blood cell [WBC] count) would mediate an association between frequency of sexual activity and quality of life in older adulthood.

METHODS

Older adults from England (N = 4,554; 2,049 men, 2,505 women; mean age = 66.25 ± 8.89 years) provided blood samples and completed self-report questionnaires on sexual activity, quality of life, and health-related behavior.

OUTCOMES

CRP (milligrams per liter), fibrinogen (grams per liter), WBC count (10⁹ cells/L), and quality of life (self-report).

RESULTS

Frequency of sexual activity had a negative association with CRP and fibrinogen. An age-moderated effect also showed that frequency of sexual activity had a negative association with WBC count in older participants in the sample (>70 years of age). CRP mediated a positive association between frequency of sexual activity and quality of life. An age-moderated mediation effect also showed that WBC count mediated the association between sexual activity and quality of life in the oldest participants in the sample. All analyses controlled for demographic, anthropometric, and health-related factors.

CLINICAL TRANSLATION

More frequent sexual activity might be a useful auxiliary approach to lowering stress-related inflammation and improving quality of life.

STRENGTHS AND LIMITATIONS

Strengths of this study include the large sample and multiple control variables. Limitations include the cross-sectional nature of the data and some loss in sample representativeness.

CONCLUSION

Findings provide evidence that more sexually active older adults exhibit an anti-inflammatory status associated with a perception of higher quality of life. Further research using prospective designs and natural experimental methods is encouraged. Allen MS. Biomarkers of Inflammation Mediate an Association Between Sexual Activity and Quality of Life in Older Adulthood. J Sex Med 2017;14:654-658.

Impact of estrogen receptor α gene and oxytocin receptor gene polymorphisms on female sexuality

Over the past decades, research attention has increasingly been paid to the neurobiological component of sexual behavior. The aim of the present study was to investigate the correlation of estrogen receptor α (ERA) gene polymorphism (rs2234693-PvuII) (T→C substitution) and oxytocin receptor gene polymorphism (rs53576) (G→A substitution) with sexuality parameters of young, healthy women. One hundred thirty-three Greek heterosexual women, students in higher education institutions, 20-25 years of age, sexually active, with normal menstrual cycles (28-35 days), were recruited in the study. Exclusion criteria were chronic and/or major psychiatric diseases, use of oral contraceptive pills (OCs), polycystic ovary syndrome (PCOS), thyroid diseases as well as drugs that are implicated in hypothalamus-pituitary-gonadal axis. T allele (wildtype) of rs2234693 (PvuII) polymorphism of ERA gene was correlated with increased levels of arousal and lubrication, whereas A allele (polymorphic) of rs53576 (OXTR) polymorphism was correlated with increased arousal levels. The simultaneous presence of both T allele of rs2234693 (PvuII) and A allele of rs53576 (OXTR) polymorphisms (T + A group) was correlated with increased arousal, orgasm levels as well as female sexual function index full score. To our knowledge, this is the first study to investigate the interaction between ERA and OXTR with regard to sexual function in women. Female sexuality is a complex behavioral trait that encompasses both biological and psychological components. It seems that variability in female sexual response stems from genetic variability that characterizes endocrine, neurotransmitter and central nervous system influences.

Measuring sperm backflow following female orgasm: a new method

Background

Human female orgasm is a vexed question in the field while there is credible evidence of cryptic female choice that has many hallmarks of orgasm in other species. Our initial goal was to produce a proof of concept for allowing females to study an aspect of infertility in a home setting, specifically by aligning the study of human infertility and increased fertility with the study of other mammalian fertility. In the latter case - the realm of oxytocin-mediated sperm retention mechanisms seems to be at work in terms of ultimate function (differential sperm retention) while the proximate function (rapid transport or cervical tenting) remains unresolved.

Method

A repeated measures design using an easily taught technique in a natural setting was used. Participants were a small (n=6), non-representative sample of females. The introduction of a sperm-simulant combined with an orgasm-producing technique using a vibrator/home massager and other easily supplied materials.

Results

The sperm flowback (simulated) was measured using a technique that can be used in a home setting. There was a significant difference in simulant retention between the orgasm (M=4.08, SD=0.17) and non-orgasm (M=3.30, SD=0.22) conditions; t (5)=7.02, p=0.001. Cohen's d=3.97, effect size r=0.89. This indicates a medium to small effect size.

Conclusions

This method could allow females to test an aspect of sexual response that has been linked to lowered fertility in a home setting with minimal training. It needs to be replicated with a larger sample size.

High interindividual and intraindividual variation of oxytocin secretion in estrous mares exposed to stallions, but no significant link to mate preferences

Oxytocin is a hormone that may not only influence reproductive mechanisms in mammals but also their social behavior, including pair bonding. We therefore tested if the concentrations of oxytocin and other hormones reveal mate preferences of 13 mares in estrus. Each mare was first exposed to two stallions (haphazardly selected out of seven) and her behavior recorded. The mare was then returned to her box (i.e., no contact to stallions during that time). Approximately 4.5 hours later, venous blood samples were collected every minute during 30 minutes preceding exposure to one of the two previously used stallions, 6 minutes during exposure, and 30 minutes after exposure back in the mare's box. The procedure was repeated in the consecutive estrus cycle, with the difference that the mare was each exposed to the other of the two stallions during oxytocin measurements. In 20 of the 26 trials, oxytocin concentrations were significantly elevated during exposure to the stallion, without significant associations to cortisol and estradiol concentrations. We found no significant association between oxytocin secretion and preferences in the previous choice situation. While estradiol concentration showed a high repeatability over the two cycles, we found considerable intraindividual differences in oxytocin and cortisol plasma concentration among the two cycles. Partially, the variation in oxytocin concentrations could be linked to the time of ovulation, with lower oxytocin plasma concentrations in mares which ovulated later than expected. In conclusion, when teasing under experimental conditions, we found high interindividual and intraindividual variation among mares in the increase of oxytocin plasma concentrations, depending on the timing of ovulation. However, oxytocin levels seemed to be no predictor of mare preference.

Hormones and Female Sexual Dysfunction: Beyond Estrogens and Androgens--Findings from the Fourth International Consultation on Sexual Medicine

INTRODUCTION

In recent years, multiple hormones have been investigated in relation to female sexual function. Because consumers can easily purchase products claiming to contain these hormones, a clear statement regarding the current state of knowledge is required.

AIM

To review the contribution of hormones, other than estrogens and androgens, to female sexual functioning and the evidence that specific endocrinopathies in women are associated with female sexual dysfunction (FSD) and to update the previously published International Society of Sexual Medicine Consensus on this topic.

METHODS

The literature was searched using several online databases with an emphasis on studies examining the physiologic role of oxytocin, prolactin, and progesterone in female sexual function and any potential therapeutic effect of these hormones. The association between common endocrine disorders, such as polycystic ovary syndrome, pituitary disorders, and obesity, and FSD also was examined.

MAIN OUTCOME MEASURES

Quality of data published in the literature and recommendations were based on the Grading of Recommendations Assessment, Development and Education system.

RESULTS

There is no evidence to support the use of oxytocin or progesterone for FSD. Treating hyperprolactinemia might lessen FSD. Polycystic ovary syndrome, obesity, and metabolic syndrome could be associated with FSD, but data are limited. There is a strong association between diabetes mellitus and FSD.

CONCLUSION

Further research is required; in particular, high-quality, large-scale studies of women with common endocrinopathies are needed to determine the impact of these prevalent disorders on female sexual function.

The central role of heat shock factor 1 in synaptic fidelity and memory consolidation

Networks of neuronal synapses are the fundamental basis for making and retaining memory. Reduced synapse number and quality correlates with loss of memory in dementia. Heat shock factor 1 (HSF1), the major transcription factor regulating expression of heat shock genes, plays a central role in proteostasis, in establishing and sustaining synaptic fidelity and function, and in memory consolidation. Support for this thesis is based on these observations: (1) heat shock induces improvements in synapse integrity and memory consolidation; (2) synaptic depolarization activates HSF1; (3) activation of HSF1 alone (independent of the canonical heat shock response) augments formation of essential synaptic elements-neuroligands, vesicle transport, synaptic scaffolding proteins, lipid rafts, synaptic spines, and axodendritic synapses; (4) HSF1 coalesces and activates memory receptors in the post-synaptic dendritic spine; (5) huntingtin or α-synuclein accumulation lowers HSF1 while HSF1 lowers huntingtin and α-synuclein aggregation-a potential vicious cycle; and (6) HSF1 agonists (including physical activity) can improve cognitive function in dementia models. Thus, via direct gene expression of synaptic elements, production of HSPs that assure high protein fidelity, and activation of other neuroprotective signaling pathways, HSF1 agonists could provide breakthrough therapy for dementia-associated disease.

Dissecting the Role of Oxytocin in the Formation and Loss of Social Relationships

Current concepts of human sociality highlight a fundamental role of the hypothalamic peptide oxytocin (OXT) in the formation and maintenance of social relationships. However, emerging evidence indicates that OXT does not invariably facilitate social bonding but also produces nonprosocial effects that may have evolved to promote offspring survival. From a mechanistic perspective, we hypothesize that OXT modulates interoceptive signals and self-referential processing, which may result in various social outcomes depending on context- and person-dependent variables such as early-life adversity. Based on this theoretical framework, we discuss translational implications for clinical trials and identify open questions for future research. Specifically, we propose that disrupted OXT signaling due to the loss of affectionate bonds may contribute to emotional disequilibrium and confer elevated risk for the onset of stress-related disorders.

Salivary oxytocin concentrations in response to running, sexual self-stimulation, breastfeeding and the TSST: The Regensburg Oxytocin Challenge (ROC) study

Intranasal oxytocin (OXT) application is emerging as a potential treatment for socio-emotional disorders associated with abnormalities in OXT system (re-) activity. The crucial identification of patients with such abnormalities could be streamlined by the assessment of basal and stimulus-induced OXT concentrations in saliva, using a simple, stress-free sampling procedure (i.e. an OXT challenge test). We therefore established the Regensburg Oxytocin Challenge (ROC) test to further validate salivary OXT concentrations as a practical, reliable and sensitive biomarker. OXT concentrations were quantified by radioimmunoassay in samples collected at home by healthy adult male and female volunteers before and after running ("Run") or sexual self-stimulation ("Sex"). In lactating women, salivary OXT concentrations were quantified before, during and after breastfeeding. Salivary OXT along with salivary cortisol and heart rate were monitored in healthy adult participants undergoing the Trier Social Stress Test (TSST). The home-based "Run" and "Sex" challenges as well as the laboratory-based TSST caused quantifiable, rapid, and consistent increases in salivary OXT (approximately 2.5-fold after 10-15min), which were similar for men and women. Breastfeeding did not result in measurably increased salivary OXT levels, probably because the short pulses of OXT release characteristic for lactation were missed. Taken together, ROC tests reliably assess the responsiveness of the OXT system (i.e., the increase in salivary OXT concentrations as compared to basal levels) to challenges such as "Run" and "Sex" at home or psychosocial stress (TSST) in the laboratory. Further studies with larger sample numbers are essentially needed in order to reveal individual differences in ROC test outcomes depending on, for example, genetic or environmental factors.

Support for the hypothesis that sexual breast stimulation is an ancestral practice and a key to understanding women's health

Women's health is seriously impacted by sexual dysfunction, mental depression, breast cancer, and gynecological cancers. Breast feeding has been found to reduce the risk of in-situ cervical cancer, endometrial cancer of the uterus, ovarian cancer, and breast cancer. This protective effect of breast feeding supports the notion that another functional use of the breast, sexual breast stimulation, promoted by women to incite their sexual arousal and orgasm, is a practice which also reduces the risk of these same cancers, and protects against sexual dysfunction and mental depression. The significance of the practice of breast sex or "sexual breast love" lies with its deeply rooted past in the founding of our species, Homo sapiens. No other species exhibits breast sex, a human cultural activity that is implicated in women's desire, sexual satisfaction, and the development of human sociality. For species females as a whole, nipple stimulation by a partner during sex, over the adult life of a female, has occurred since the inception of H. sapiens, so that the failure to engage in this activity is counter to a species typical practice and endangers women's health. Breast sex results in nipple erection, and may micmic the effects of breast feeding, causing an increase of oxytocin in the body. Breast sex is an enriched type of sexuality that enables love between the sexes and the pair bond. The intimacy of breast sex creates a common ground of sexual knowledge, allowing empathy, cooperation, commitment, and communication. It induces reciprocity and therefore happiness. With breast sex, there is an increase of the positive emotions over the chimpanzees, promoting advanced cognition. Research into whether oxytocin release is caused by stimulation of the breasts in non-lactating women is inconclusive, but cultural studies demonstrate that breast stimulation induces sexual arousal, and research has shown that sexual arousal is associated with oxytocin release.

60 YEARS OF NEUROENDOCRINOLOGY: The posterior pituitary, from Geoffrey Harris to our present understanding

Geoffrey Harris pioneered our understanding of the posterior pituitary, mainly with experiments that involved the electrical stimulation of the supraoptico-hypophysial tract. In the present essay, we explain how his observations included clues to the pulsatile nature of the oxytocin signal - clues that were followed up by subsequent workers, including his students and their students. These studies ultimately led to our present understanding of the milk-ejection reflex and of the role of oxytocin in parturition. Discoveries of wide significance followed, including: the recognition of the importance of pulsatile hormone secretion; the recognition of the importance of stimulus-secretion coupling mechanisms in interpreting the patterned electrical activity of neurons; the physiological importance of peptide release in the brain; the recognition that peptide release comes substantially from dendrites and can be regulated independently of nerve terminal secretion; and the importance of dynamic morphological changes to neuronal function in the hypothalamus. All of these discoveries followed from the drive to understand the milk-ejection reflex. We also reflect on Harris's observations on vasopressin secretion, on the effects of stress, and on oxytocin secretion during sexual activity.

Oxytocin: parallel processing in the social brain?

Early studies attempting to disentangle the network complexity of the brain exploited the accessibility of sensory receptive fields to reveal circuits made up of synapses connected both in series and in parallel. More recently, extension of this organisational principle beyond the sensory systems has been made possible by the advent of modern molecular, viral and optogenetic approaches. Here, evidence supporting parallel processing of social behaviours mediated by oxytocin is reviewed. Understanding oxytocinergic signalling from this perspective has significant implications for the design of oxytocin-based therapeutic interventions aimed at disorders such as autism, where disrupted social function is a core clinical feature. Moreover, identification of opportunities for novel technology development will require a better appreciation of the complexity of the circuit-level organisation of the social brain.

Oxytocin: recent developments

Oxytocin is a neurohypophyseal hormone that is produced centrally by neurons in the paraventricular nucleus and supraoptic nucleus of the hypothalamus. It is released directly into higher brain centres and into the peripheral circulation where it produces a multitude of effects. Classically, oxytocin is known for inducing uterine contractions at parturition and milk ejection during suckling. Oxytocin also acts in a species and gender specific manner as an important neuromodulator. It can affect behaviours associated with stress and anxiety, as well social behaviours including sexual and relationship behaviours, and maternal care. Additionally, oxytocin has been shown to have a variety of physiological roles in peripheral tissues, many of which appear to be modulated largely by locally produced oxytocin, dispelling the notion that oxytocin is a purely neurohypophyseal hormone. Oxytocin levels are altered in several diseases and the use of oxytocin or its antagonists have been identified as a possible clinical intervention in the treatment of mood disorders and pain conditions, some cancers, benign prostatic disease and osteoporosis. Indeed, oxytocin has already been successful in clinical trials to treat autism and schizophrenia. This review will report briefly on the known functions of oxytocin, it will discuss in depth the data from recent clinical trials and highlight future targets for oxytocinergic modulation.

Oxytocin increases VTA activation to infant and sexual stimuli in nulliparous and postpartum women

After giving birth, women typically experience decreased sexual desire and increased responsiveness to infant stimuli. These postpartum changes may be viewed as a trade-off in reproductive interests, which could be due to alterations in brain activity including areas associated with reward. The goal of this study was to describe the roles of oxytocin and parity on reward area activation in response to reproductive stimuli, specifically infant and sexual images. Because they have been shown to be associated with reward, the ventral tegmental area (VTA) and nucleus accumbens (NAc) were targeted as areas of expected alterations in activity. Oxytocin was chosen as a potential mediator of reproductive trade-offs because of its relationship to both mother-infant interactions, including breastfeeding and bonding, and sexual responses. We predicted that postpartum women would show higher reward area activation to infant stimuli and nulliparous women would show higher activation to sexual stimuli and that oxytocin would increase activation to infant stimuli in nulliparous women. To test this, we measured VTA and NAc activation using fMRI in response to infant photos, sexual photos, and neutral photos in 29 postpartum and 30 nulliparous women. Participants completed the Sexual Inhibition (SIS) and Sexual Excitation (SES) Scales and the Brief Index of Sexual Function for Women (BISF-W), which includes a sexual desire dimension, and received either oxytocin or placebo nasal spray before viewing crying and smiling infant and sexual images in an fMRI scanner. For both groups of women, intranasal oxytocin administration increased VTA activation to both crying infant and sexual images but not to smiling infant images. We found that postpartum women showed lower SES, higher SIS, and lower sexual desire compared to nulliparous women. Across parity groups, SES scores were correlated with VTA activation and subjective arousal ratings to sexual images. In postpartum women, sexual desire was positively correlated with VTA activation to sexual images and with SES. Our findings show that postpartum decreases in sexual desire may in part be mediated by VTA activation, and oxytocin increased activation of the VTA but not NAc in response to sexual and infant stimuli. Oxytocin may contribute to the altered reproductive priorities in postpartum women by increasing VTA activation to salient infant stimuli.

The role of oxytocin in male and female reproductive behavior

Oxytocin (OT) is a nonapeptide with an impressive variety of physiological functions. Among them, the 'prosocial' effects have been discussed in several recent reviews, but the direct effects on male and female sexual behavior did receive much less attention so far. As our contribution to honor the lifelong interest of Berend Olivier in the control mechanisms of sexual behavior, we decided to explore the role of OT in the present review. In the successive sections, some physiological mechanisms and the 'pair-bonding' effects of OT will be discussed, followed by sections about desire, female appetitive and copulatory behavior, including lordosis and orgasm. At the male side, the effects on erection and ejaculation are reviewed, followed by a section about 'premature ejaculation' and a possible role of OT in its treatment. In addition to OT, serotonin receives some attention as one of the main mechanisms controlling the effects of OT. In the succeeding sections, the importance of OT for 'the fruits of labor' is discussed, as it plays an important role in both maternal and paternal behavior. Finally, we pay attention to an intriguing brain area, the ventrolateral part of the ventromedial hypothalamic nucleus (VMHvl), apparently functioning in both sexual and aggressive behavior, which are at first view completely opposite behavioral systems.

Differential effects of intranasal oxytocin on sexual experiences and partner interactions in couples

Knowledge about the effects of the neuropeptide oxytocin (OXT) on human sexual behaviors and partner interactions remains limited. Based on our previous studies, we hypothesize that OXT should be able to positively influence parameters of sexual function and couple interactions. Employing a naturalistic setting involving 29 healthy heterosexual couples (n=58 participants), we analyzed the acute effects of intranasally administered OXT (24IU) on sexual drive, arousal, orgasm and refractory aspects of sexual behavior together with partner interactions. Data were assessed by psychometric instruments (Acute Sexual Experiences Scale, Arizona Sexual Experience Scale) as well as biomarkers, such as cortisol, α-amylase and heart rate. Intranasal OXT administration did not alter "classical" parameters of sexual function, such as sexual drive, arousal or penile erection and lubrication. However, analysis of variance and a hierarchical linear model (HLM) revealed specific effects related to the orgasmic/post-orgasmic interval as well as parameters of partner interactions. According to HLM analysis, OXT increased the intensity of orgasm, contentment after sexual intercourse and the effect of study participation. According to ANOVA analysis, these effects were more pronounced in men. Men additionally indicated higher levels of sexual satiety after sexual intercourse with OXT administration. Women felt more relaxed and subgroups indicated better abilities to share sexual desires or to empathize with their partners. The effect sizes were small to moderate. Biomarkers indicated moderate psychophysiological activation but were not affected by OXT, gender or method of contraception. Using a naturalistic setting, intranasal OXT administration in couples exerted differential effects on parameters of sexual function and partner interactions. These results warrant further investigations, including subjects with sexual and relationship problems.

Genetic influences on adolescent sexual behavior: Why genes matter for environmentally oriented researchers

There are dramatic individual differences among adolescents in how and when they become sexually active adults, and early sexual activity is frequently cited as a cause of concern for scientists, policymakers, and the general public. Understanding the causes and developmental impact of adolescent sexual activity can be furthered by considering genes as a source of individual differences. Quantitative behavioral genetics (i.e., twin and family studies) and candidate gene association studies now provide clear evidence for the genetic underpinnings of individual differences in adolescent sexual behavior and related phenotypes. Genetic influences on sexual behavior may operate through a variety of direct and indirect mechanisms, including pubertal development, testosterone levels, and dopaminergic systems. Genetic differences may be systematically associated with exposure to environments that are commonly treated as causes of sexual behavior (gene-environment correlation). Possible gene-environment correlations pose a serious challenge for interpreting the results of much behavioral research. Multivariate, genetically informed research on adolescent sexual behavior compares twins and family members as a form of quasi experiment: How do twins who differ in their sexual experiences differ in their later development? The small but growing body of genetically informed research has already challenged dominant assumptions regarding the etiology and sequelae of adolescent sexual behavior, with some studies indicating possible positive effects of teenage sexuality. Studies of Gene × Environment interaction may further elucidate the mechanisms by which genes and environments combine to shape the development of sexual behavior and its psychosocial consequences. Overall, the existence of heritable variation in adolescent sexual behavior has profound implications for environmentally oriented theory and research.

Oxytocin, motivation and the role of dopamine

The hypothalamic neuropeptide oxytocin has drawn the attention of scientists for more than a century. The understanding of the function of oxytocin has expanded dramatically over the years from a simple peptide adept at inducing uterine contractions and milk ejection to a complex neuromodulator with a capacity to shape human social behavior. Decades of research have outlined oxytocin's ability to enhance intricate social activities ranging from pair bonding, sexual activity, affiliative preferences, and parental behaviors. The precise neural mechanisms underlying oxytocin's influence on such behaviors have just begun to be understood. Research suggests that oxytocin interacts closely with the neural pathways responsible for processing motivationally relevant stimuli. In particular, oxytocin appears to impact dopaminergic activity within the mesocorticolimbic dopamine system, which is crucial not only for reward and motivated behavior but also for the expression of affiliative behaviors. Though most of the work performed in this area has been done using animal models, several neuroimaging studies suggest similar relationships may be observed in humans. In order to introduce this topic further, this paper will review the recent evidence that oxytocin may exert some of its social-behavioral effects through its impact on motivational networks.

Sexuality after breast reconstruction post mastectomy

BACKGROUND

Sexual dysfunction is a medical condition that can lead to relationship issues as well as depression and has a somatoform basis. It is estimated to affect 49 % of Brazilian women. Studies have shown that both cancer diagnosis and its surgical treatment (mastectomy) affect women psychologically and can lead to psychiatric disorders. The aim of this study was to evaluate and compare sexuality in women who underwent mastectomy alone with those who underwent breast reconstruction after mastectomy.

METHOD

This descriptive transversal study analyzed two groups of patients, one with 17 women after mastectomy alone and another with 19 women who underwent breast reconstruction post mastectomy. The patients ranged in age from 18 to 60 years old. The exclusion criteria were illiteracy; ongoing chemotherapy, radiotherapy, or psychiatric treatment; or if any surgery had been performed the previous year. All patients were from the Gynecology and Plastic Surgery Department of the Federal University of São Paulo. They voluntarily answered the FSFI (Female Sexual Function Index) questionnaire. Statistical analyses were performed using Student's t test and Pearson's coefficient, and the significance level used was p < 0.05.

RESULTS

Data showed a lower FSFI score for the mastectomy-alone group compared to the breast reconstruction group (median = 10.15 ± 2.636 and 22.44 ± 3.055, respectively; p = 0.0057). There was no relationship established between the scores and postoperative time (post, p = 0.9382; pre, p = 0.2142) or between scores and remuneration income (post, p = 0.7699; pre, p = 0.5245), stable relationship (post, p = 0.2613; pre, p = 0.5245), and age (post, p = 0.3951; pre, p = 0.8427) for both groups. Mean age has shown no significant difference (p = 0.4740; median post = 47.71 ± 2.012; medina pre = 46.69 ± 1.809).

CONCLUSION

An improvement in sexual function has been observed in patients who underwent breast reconstruction after mastectomy, probably as a result of better self-esteem as well as body image, both of which are affected by a mastectomy. The aesthetic results were evaluated using a questionnaire, and all the patients answered positively.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .