Intrinsic links among sex, emotion, and reproduction

Developmental programming of reproduction in the female animal

Successful reproduction is a cornerstone in food animal industry in order to sustain food production for human. Therefore, various methods focusing on genetics and postnatal environment have been identified and applied to improve fertility in livestock. Yet there is evidence indicating that environmental factors during prenatal and/or neonatal life can also impact the function of reproductive system and fertility in the animals during adulthood, which is called the developmental programming of reproduction. The current review summarizes data associated with the developmental origins of reproduction in the female animals. In this regard, this review focuses on the effect of plane of nutrition, maternal body condition, hypoxia, litter size, maternal age, parity, level of milk production and milk components, lactocrine signaling, stress, thermal stress, exposure to androgens, endocrine disrupting chemicals, mycotoxins and pollutants, affliction with infection and inflammation, and maternal gut microbiota during prenatal and neonatal periods on the neuroendocrine system, puberty, health of reproductive organs and fertility in the female offspring. It is noteworthy that these prenatal and neonatal factors do not always exert their effects on the reproductive performance of the female by compromising the development of organs directly related to reproductive function such as hypothalamus, pituitary, ovary, oviduct and uterus. Since they can impair the development of non-reproductive organs and systems modulating reproductive function as well (e.g., metabolic system and level of milk yield in dairy animals). Furthermore, when these factors affect the epigenetics of the offspring, their adverse effects will not be limited to one generation and can transfer transgenerationally. Hence, pinpointing the factors influencing developmental programming of reproduction and considering them in management of livestock operations could be a potential strategy to help improve fertility in food animals.

The Emerging Therapeutic Potential of Kisspeptin and Neurokinin B

Kisspeptin (KP) and neurokinin B (NKB) are neuropeptides that govern the reproductive endocrine axis through regulating hypothalamic gonadotropin-releasing hormone (GnRH) neuronal activity and pulsatile GnRH secretion. Their critical role in reproductive health was first identified after inactivating variants in genes encoding for KP or NKB signaling were shown to result in congenital hypogonadotropic hypogonadism and a failure of pubertal development. Over the past 2 decades since their discovery, a wealth of evidence from both basic and translational research has laid the foundation for potential therapeutic applications. Beyond KP's function in the hypothalamus, it is also expressed in the placenta, liver, pancreas, adipose tissue, bone, and limbic regions, giving rise to several avenues of research for use in the diagnosis and treatment of pregnancy, metabolic, liver, bone, and behavioral disorders. The role played by NKB in stimulating the hypothalamic thermoregulatory center to mediate menopausal hot flashes has led to the development of medications that antagonize its action as a novel nonsteroidal therapeutic agent for this indication. Furthermore, the ability of NKB antagonism to partially suppress (but not abolish) the reproductive endocrine axis has supported its potential use for the treatment of various reproductive disorders including polycystic ovary syndrome, uterine fibroids, and endometriosis. This review will provide a comprehensive up-to-date overview of the preclinical and clinical data that have paved the way for the development of diagnostic and therapeutic applications of KP and NKB.

Maintaining vulvar, vaginal and perineal health: Clinical considerations

Knowledge of female genital anatomy and physiology is often inadequate or incorrect among women. Precise patient-physician conversations can be inhibited by a reluctance or inability to speak accurately about the vulva and vagina, with the terms often being used interchangeably. There is a paucity of scientific evidence and clinical guidelines to support women and physicians in ensuring best practices in feminine hygiene. In this review, the unmet needs in the field are highlighted. Evidence is provided for the complex array of physiological and pathological systems, mechanisms and behaviours that either protect or, if inappropriate, predispose the vulva and vagina to infections, irritation or other conditions. The need for attention to perineal health is recommended, given the interdependence of perineal and vulvar microbiota and the risk of colonic pathogens reaching the vulva and the vagina. Differences in feminine hygiene practices can vary widely across the world and among varying age groups, and suboptimal habits (such as vaginal douching or the use of certain cleansers) can be associated with increased risks of vulvar and vaginal conditions. Critical areas for discussion when advising women on their intimate health include: advice surrounding aesthetic vulvar cosmetic trends (such as depilation and genital cosmetic surgery), bowel health and habits, and protection against sexually transmitted infections. Routine, once-daily (maximum twice-daily) washing of the vulva with a pH-balanced, mild cleanser is optimal, ideally soon after bowel voiding, when feasible. Due to the finely balanced ecosystems of the vulva, the vagina and the perineal area, a scientific and clinical perspective is essential when determining the most appropriate vulvar cleansers based on their components. Correct intimate care may contribute to improved genital and sexual health and overall well-being. An increased awareness of correct practices will empower women to be the advocates of their own intimate health.

Dyadic adjustment and the relationship between sexual self-consciousness and sexual dysfunction in individuals with spinal cord injuries: A descriptive study

PURPOSE

This study was conducted to determine the dyadic adjustment between individuals with SCI and their spouses and the relationship between their sexual self-consciousness and sexual life and to evaluate it according to the objectification theory.

METHOD

This descriptive and cross-sectional study was conducted with 131 married individuals with SCI registered in the physical therapy and rehabilitation outpatient clinic of a university hospital between February 2020 and April 2021. The data of the study were collected using a Descriptive Information Form, the American Spinal Injury Association Impairment Scale (ASIA), the Dyadic Adjustment Scale (DAS), the Sexual Self-Consciousness Scale (SSCS), and the Arizona Sexual Experiences Scale (ASEX). In the study, the predictors of the sexual life of individuals with SCI were evaluated with the Stepwise Multiple Linear Regression analysis. In addition, predictors of sexual dysfunction in individuals with SCI were evaluated by the logistic regression analysis. The results were discussed within the framework of objectification theory.

RESULTS

According to the results of the study, .67.2% of the individuals with spinal cord injuries experienced sexual functionality problems; increased age, falling injuries, and being in ASIA grade A increased sexual self-awareness and sexual dysfunction; and being a male with SCI increased sexual focus. It was found that the adjustment between individuals with SCI and their spouses was a predictor that significantly reduced sexual embarrassment, sexual self-consciousness, and sexual dysfunction and that the strong adjustment between couples was an important factor for the prevention of sexual dysfunction development.

CONCLUSION

It was found that most individuals with spinal cord injuries experienced sexual dysfunction. The importance of dyadic adjustment and sexual self-consciousness has come to the fore in the sexual life of these individuals.

Distinct Emotional and Cardiac Responses to Audio Erotica between Genders

Emotional and cardiac responses to audio erotica and their gender differences are relatively unclear in the study of the human sexual response. The current study was designed to investigate gender differences regarding positive and negative emotional responses to erotica, as well as its association with cardiac response. A total of 40 healthy participants (20 women) were exposed to erotic, neutral, and happy audio segments during which emotions and heart rate changes were evaluated. Our data showed distinct emotional responses to erotica between genders, in which women reported a higher level of shame than men and rated erotic audios as less pleasant than happy audios. Meanwhile, men reported erotic and happy audios as equally pleasant. These results were independent of cardiac changes, as both sexes demonstrated comparable heart rate deceleration when exposed to erotica relative to neutral and happy stimuli. Our results highlight the role of sociocultural modulation in the emotional response to erotica.

Invited review: Translating kisspeptin and neurokinin B biology into new therapies for reproductive health

The reproductive neuropeptide kisspeptin has emerged as the master regulator of mammalian reproduction due to its key roles in the initiation of puberty and the control of fertility. Alongside the tachykinin neurokinin B and the endogenous opioid dynorphin, these peptides are central to the hormonal control of reproduction. Building on the expanding body of experimental animal models, interest has flourished with human studies revealing that kisspeptin administration stimulates physiological reproductive hormone secretion in both healthy men and women, as well as patients with common reproductive disorders. In addition, emerging therapeutic roles based on neurokinin B for the management of menopausal flushing, endometriosis and uterine fibroids are increasingly recognised. In this review, we focus on kisspeptin and neurokinin B and their potential application as novel clinical strategies for the management of reproductive disorders.

Pregnancy After Concussion: A Clarion Call for Attention?

OBJECTIVE

Emerging research shows that women who sustain a mild traumatic brain injury, also termed concussion, have a higher risk of menstrual irregularities and sexual dysfunctions. However, no research exists on how these reproductive disruptions affect women's subsequent pregnancies. The objective of this study was to evaluate pregnancy outcomes after concussion in a cohort of reproductive-aged women (aged 18-45 years), 24 months post-injury. We hypothesized that, compared with their extremity-injured peers in the same cohort, women with concussion will have lower incidence of pregnancies.

SETTING

Emergency department of a level 1 trauma center.

PARTICIPANTS

Women of reproductive age (aged 18-45 years) seeking care for concussion or extremity injury.

DESIGN

Longitudinal cohort study that used data collected at 3 distinct time points: t0, baseline: an original cohort of 245 women recruited in January to July 2017 for exposure assessment; t1, 6(+4) weeks post-injury: evaluation of self-reported postinjury menstrual and sexual changes for subgroup analyses-data collected in March to September 2017 ( n = 135); t2, 24 months post-injury: March 2020 chart review for documentation of pregnancies/pregnancy-related events ( N = 245).

MAIN MEASURE

Poisson regression estimates used to model the incidence rate (IR) of pregnancies, comparing concussion with extremity injury.

RESULTS

We reviewed the charts of 254 women from the t0 cohort. After excluding 9 patients who were either deceased or missing relevant data, we had the 245 (96.5%) charts of 102 concussed and 143 extremity-injured study participants. After adjusting for race and obstetric history, women with concussion had 80% lower incidence of pregnancies than their extremity-injured peers (adjusted [adj] IR = 0.20; 95% CI: 0.07-0.59; P = .003). When we excluded women who were using birth control, the IR of pregnancy for women with concussions was 76% lower than for those who had sustained extremity injuries (adj IR = 0.24; 95% CI: 0.07-0.81; P = .02). Pregnancy incidence remained consistently lower for concussed women in additional sensitivity analyses excluding assault/domestic violence victims and those with a prior/new concussion at t0 and t2. Subgroup analyses of the 135 women who had experienced menstrual and/or sexual dysfunctions at t1 showed 84% reduced incidence of pregnancy for women with concussions compared with those who had sustained an extremity injury (adj IR = 0.16; 95% CI: 0.04-0.73; P = .02).

CONCLUSION AND RELEVANCE

Our study potentially serves as a clarion call to understand the long-term reproductive effects of female concussions.

Current Perspectives on Kisspeptins Role in Behaviour

The neuropeptide kisspeptin is now well-established as the master regulator of the mammalian reproductive axis. Beyond the hypothalamus, kisspeptin and its cognate receptor are also extensively distributed in extra-hypothalamic brain regions. An expanding pool of animal and human data demonstrates that kisspeptin sits within an extensive neuroanatomical and functional framework through which it can integrate a range of internal and external cues with appropriate neuroendocrine and behavioural responses. In keeping with this, recent studies reveal wide-reaching effects of kisspeptin on key behaviours such as olfactory-mediated partner preference, sexual motivation, copulatory behaviour, bonding, mood, and emotions. In this review, we provide a comprehensive update on the current animal and human literature highlighting the far-reaching behaviour and mood-altering roles of kisspeptin. A comprehensive understanding of this important area in kisspeptin biology is key to the escalating development of kisspeptin-based therapies for common reproductive and related psychological and psychosexual disorders.

Combined exposure to environmentally relevant copper and 2,2'-dithiobis-pyridine induces significant reproductive toxicity in male guppy (Poecilia reticulata)

Metal pyrithiones (MePTs), the most widely used biocides in antifouling paints (AFs) coated on the hulls, are usually used in combination with Cu-containing substances. In the aquatic environment, 2,2'-dithiobis-pyridine ((PS)₂), the main degradation product of MePTs, and Cu usually coexist. However, their combined impacts on aquatic organisms are unclear. This study exposed male guppy (Poecilia reticulata) to an environmentally realistic concentration of Cu (10 μg/L) alone or Cu (10 μg/L) combined with 20, 200, and 2000 ng/L (PS)₂ to explore their combined reproductive toxicity. The results showed that co-exposure to Cu and (PS)₂ increased Cu accumulation in the fish body in a dose-dependent manner and induced obvious spermatozoon apoptosis and necrosis, which was mediated by the peroxidation and caspase activation. Compared to Cu alone, co-exposure to Cu and 200, 2000 ng/L (PS)₂ significantly decreased the testosterone level and collapsed spermatogenesis, and depressed male's sexual interest and mating behavior were observed in three co-exposure groups. Moreover, co-exposure to Cu and (PS)₂ increased the disturbance on cyp19a and cyp19b transcription and suppressed the "display" reproductive behavior. Eventually, co-exposure to Cu and (PS)₂ caused male reproductive failure. Therefore, the concurrence of Cu and (PS)₂ induced significant reproductive toxicity in male guppies and would threaten the sustainability of fish populations. Considering the extensive usage of MePTs products in the AFs, their ecological risk warrants more evaluation.

Abnormal Functional Connectivity Between the Left Medial Superior Frontal Gyrus and Amygdala Underlying Abnormal Emotion and Premature Ejaculation: A Resting State fMRI Study

Introduction

Premature ejaculation (PE) is a common sexual dysfunction and is found to be associated with abnormal emotion. The amygdala plays an important role in the processing of emotion. The process of ejaculation is found to be mediated by the frontal-limbic neural circuits. However, the correlations between PE and emotion are still unclear.

Methods

Resting-state functional magnetic resonance imaging (rs-fMRI) data were acquired in 27 PE patients with stable emotion (SPE), 27 PE patients with abnormal emotion (NPE), and 30 healthy controls (HC). We used rs-fMRI to explore the underlying neural mechanisms in SPE, NPE, and HC by measuring the functional connectivity (FC). Differences of FC values among the three groups were compared when choosing bilateral amygdala as the regions of interest (ROIs). We also explored the correlations between the brain regions showing altered FC values and scores of the premature ejaculation diagnostic tool (PEDT)/Eysenck Personality Inventory about neuroticism (EPQ-N) in the PE group.

Results

When the left amygdala was chosen as the ROI, the SPE group exhibited an increased FC between the left medial superior frontal gyrus (SFGmed) and amygdala compared with the NPE or HC group. When the right amygdala was chosen as the ROI, the NPE group exhibited a decreased FC between the left SFGmed and right amygdala compared with the HC group. In addition, FC values of the left SFGmed had positive correlations with PEDT and negative correlations with EPQ-N scores in the PE group. Moreover, FC values of the left superior temporal gyrus had positive correlations with EPQ-N scores in the PE group.

Conclusion

The increased FC values between the left SFGmed and amygdala could reflect a compensatory cortical control mechanism with the effect of stabilized emotion in the limbic regions of PE patients. Abnormal FC between these brain regions could play a critical role in the physiopathology of PE and could help us in dividing PE into more subtypes.

Functions of galanin, spexin and kisspeptin in metabolism, mood and behaviour

The bioactive peptides galanin, spexin and kisspeptin have a common ancestral origin and their pathophysiological roles are increasingly the subject of investigation. Evidence suggests that these bioactive peptides play a role in the regulation of metabolism, pancreatic β-cell function, energy homeostasis, mood and behaviour in several species, including zebrafish, rodents and humans. Galanin signalling suppresses insulin secretion in animal models (but not in humans), is potently obesogenic and plays putative roles governing certain evolutionary behaviours and mood modulation. Spexin decreases insulin secretion and has potent anorectic, analgesic, anxiolytic and antidepressive-like effects in animal models. Kisspeptin modulates glucose-stimulated insulin secretion, food intake and/or energy expenditure in animal models and humans. Furthermore, kisspeptin is implicated in the control of reproductive behaviour in animals, modulation of human sexual and emotional brain processing, and has antidepressive and fear-suppressing effects. In addition, galanin-like peptide is a further member of the galaninergic family that plays emerging key roles in metabolism and behaviour. Therapeutic interventions targeting galanin, spexin and/or kisspeptin signalling pathways could therefore contribute to the treatment of conditions ranging from obesity to mood disorders. However, many gaps and controversies exist, which must be addressed before the therapeutic potential of these bioactive peptides can be established.

Distinct dimensions of emotion in the human brain and their representation on the cortical surface

We experience a rich variety of emotions in daily life, and a fundamental goal of affective neuroscience is to determine how these emotions are represented in the brain. Recent psychological studies have used naturalistic stimuli (e.g., movies) to reveal high dimensional representational structures of diverse daily-life emotions. However, relatively little is known about how such diverse emotions are represented in the brain because most of the affective neuroscience studies have used only a small number of controlled stimuli. To reveal that, we measured functional MRI to obtain blood-oxygen-level-dependent (BOLD) responses from human subjects while they watched emotion-inducing audiovisual movies over a period of 3 hours. For each of the one-second movie scenes, we annotated the movies with respect to 80 emotions selected based on a wide range of previous emotion literature. By quantifying canonical correlations between the emotion ratings and the BOLD responses, the results suggest that around 25 distinct dimensions (ranging from 18 to 36 and being subject-dependent) of the emotion ratings contribute to emotion representations in the brain. For demonstrating how the 80 emotion categories were represented in the cortical surface, we visualized a continuous semantic space of the emotion representation and mapped it on the cortical surface. We found that the emotion categories were changed from unimodal to transmodal regions on the cortical surface. This study presents a cortical representation of a rich variety of emotion categories, which covers many of the emotional experiences of daily living.

Neuroendocrine Mechanisms Involved in Male Sexual and Emotional Behavior

OBJECTIVE

The aim of this narrative review was to analyze the role played by brain areas, neurohormones and neurotransmitters in the regulation of emotional and sexual behavior in the male.

METHODS

We analyzed the currently available literature dealing with brain structures, neurotransmitters and neurohormones involved in the regulation of emotional and sexual behavior in the male.

RESULTS

A common brain pathway is involved in these two aspects. The Hippocampus seems to control the signals coming from the external environment, while the amygdala and the hypothalamus control the response to social stimuli. Stimulation of amygdala in the animal models increases sexual performance, while it triggers violent emotional responses. Stimulation of the hypothalamus causes reactions of violent anger and increases sexual activity. Catecholaminergic stimulation of the amygdala and hypothalamus increases emotional and sexual behavior, while serotonin plays an inhibitory role. Cholinergic inhibition leads to a suppression of copulatory activity, while the animal becomes hyperemotive. Opioids, such as β-endorphin and met-enkephalin, reduce copulatory activity and induce impotence. Gonadal steroid hormones, such as estrogen in female and testosterone in male, which play a major role in the control of sexual behavior and gender difference have been highlighted in this review. Vasopressin, oxytocin and their receptors are expressed in high density in the "social behavior neural network" and play a role as signal system controlling social behavior. Finally, the neuropeptide kisspeptin and its receptors, located in the limbic structures, mediate olfactory control of the gonadotropic axis.

CONCLUSION

Further studies are needed to evaluate possible implications in the treatment of psychosexual and reproductive disorders.

NKB signaling in the posterodorsal medial amygdala stimulates gonadotropin release in a kisspeptin-independent manner in female mice

Neurokinin B (NKB) signaling is critical for reproduction in all studied species. The existing consensus is that NKB induces GnRH release via kisspeptin (Kiss1) stimulation in the arcuate nucleus. However, the stimulatory action of NKB is dependent on circulating estrogen (E2) levels, without which, NKB inhibits luteinizing hormone (LH) release. Importantly, the evidence supporting the kisspeptin-dependent role of NKB, derives from models of persistent hypogonadal state [e.g. Kiss1r knock-out (KO) mice], with reduced E2 levels. Here, we demonstrate that in the presence of E2, NKB signaling induces LH release in a kisspeptin-independent manner through the activation of NK3R (NKB receptor) neurons in the posterodorsal medial amygdala (MePD). Importantly, we show that chemogenetic activation of MePD Kiss1 neurons induces LH release, however, the stimulatory action of NKB in this area is Kiss1 neuron-independent. These results document the existence of two independent neuronal circuitries within the MePD that regulate reproductive function in females.

Editorial note

This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Modulations of human resting brain connectivity by kisspeptin enhance sexual and emotional functions

BACKGROUND

Resting brain connectivity is a crucial component of human behavior demonstrated by disruptions in psychosexual and emotional disorders. Kisspeptin, a recently identified critical reproductive hormone, can alter activity in certain brain structures but its effects on resting brain connectivity and networks in humans remain elusive.

METHODS

We determined the effects of kisspeptin on resting brain connectivity (using functional neuroimaging) and behavior (using psychometric analyses) in healthy men, in a randomized double-blinded 2-way placebo-controlled study.

RESULTS

Kisspeptin's modulation of the default mode network (DMN) correlated with increased limbic activity in response to sexual stimuli (globus pallidus r = 0.500, P = 0.005; cingulate r = 0.475, P = 0.009). Furthermore, kisspeptin's DMN modulation was greater in men with less reward drive (r = -0.489, P = 0.008) and predicted reduced sexual aversion (r = -0.499, P = 0.006), providing key functional significance. Kisspeptin also enhanced key mood connections including between the amygdala-cingulate, hippocampus-cingulate, and hippocampus-globus pallidus (all P < 0.05). Consistent with this, kisspeptin's enhancement of hippocampus-globus pallidus connectivity predicted increased responses to negative stimuli in limbic structures (including the thalamus and cingulate [all P < 0.01]).

CONCLUSION

Taken together, our data demonstrate a previously unknown role for kisspeptin in the modulation of functional brain connectivity and networks, integrating these with reproductive hormones and behaviors. Our findings that kisspeptin modulates resting brain connectivity to enhance sexual and emotional processing and decrease sexual aversion, provide foundation for kisspeptin-based therapies for associated disorders of body and mind.

FUNDING

NIHR, MRC, and Wellcome Trust.

Kisspeptin and the control of emotions, mood and reproductive behaviour

Reproduction is fundamental for the survival of all species and requires meticulous synchronisation of a diverse complement of neural, endocrine and related behaviours. The reproductive hormone kisspeptin (encoded by the KISS1/Kiss1 gene) is now a well-established orchestrator of reproductive hormones, acting upstream of gonadotrophin-releasing hormone (GnRH) at the apex of the hypothalamic–pituitary–gonadal (HPG) reproductive axis. Beyond the hypothalamus, kisspeptin is also expressed in limbic and paralimbic brain regions, which are areas of the neurobiological network implicated in sexual and emotional behaviours. We are now forming a more comprehensive appreciation of extra-hypothalamic kisspeptin signalling and the complex role of kisspeptin as an upstream mediator of reproductive behaviours, including olfactory-driven partner preference, copulatory behaviour, audition, mood and emotion. An increasing body of research from zebrafish to humans has implicated kisspeptin in the integration of reproductive hormones with an overall positive influence on these reproductive behaviours. In this review, we critically appraise the current literature regarding kisspeptin and its control of reproductive behaviour. Collectively, these data significantly enhance our understanding of the integration of reproductive hormones and behaviour and provide the foundation for kisspeptin-based therapies to treat related disorders of body and mind.