Dopamine and sexual behavior

Cellular and molecular mechanisms of action of ovarian steroid hormones II: Regulation of sexual behavior in female rodents

Female sexual behaviors in rodents (lordosis and appetitive or "proceptive" behaviors) are induced through a genomic mechanism by the sequential actions of estradiol (E2) and progesterone (P), or E2 and testosterone (T) at their respective receptors. However, non-steroidal agents, such as gonadotropin-releasing hormone (GnRH), Prostaglandin E2 (PGE2), noradrenaline, dopamine, oxytocin, α-melanocyte stimulating hormone, nitric oxide, leptin, apelin, and others, facilitate different aspects of female sexual behavior through their cellular and intracellular effects at the membrane and genomic levels in ovariectomized rats primed with E2. These neurotransmitters often act as intermediaries of E2 and P (or T). The classical model of steroid hormone action through intracellular receptor binding has been complemented by an alternative scenario wherein the steroid functions as a transcription factor after binding the receptor protein to DNA. Another possible mechanism occurs through the activation of second messenger systems (cyclic AMP, cyclic GMP, calcium), which subsequently initiate phosphorylation events via diverse kinase systems (protein kinases A, G, or C). These kinases target the progesterone receptor (PR) or associated effector proteins that connect the PR to the trans-activation machinery. This may also happen to the androgen receptor (AR). In addition, other cellular mechanisms could be involved since the chemical structure of these non-steroidal agents causes a change in their lipophobicity that prevents them from penetrating the cell and exerting direct transcriptional effects; however, they can exert effects on different components of the cell membrane activating a cross-talk between the cell membrane and the regulation of the transcriptional mechanisms.

The Chromosome-level Genome Provides Insights into the Evolution and Adaptation of Extreme Aggression

Extremely aggressive behavior, as the special pattern, is rare in most species and characteristic as contestants severely injured or killed ending the combat. Current studies of extreme aggression are mainly from the perspectives of behavioral ecology and evolution, while lacked the aspects of molecular evolutionary biology. Here, a high-quality chromosome-level genome of the parasitoid Anastatus disparis was provided, in which the males exhibit extreme mate-competition aggression. The integrated multiomics analysis highlighted that neurotransmitter dopamine overexpression, energy metabolism (especially from lipid), and antibacterial activity are likely major aspects of evolutionary formation and adaptation for extreme aggression in A. disparis. Conclusively, our study provided new perspectives for molecular evolutionary studies of extreme aggression as well as a valuable genomic resource in Hymenoptera.

On the basis of sex and sleep: the influence of the estrous cycle and sex on sleep-wake behavior

The recurrent hormonal fluctuations within reproductive cycles impact sleep-wake behavior in women and in rats and mice used in preclinical models of sleep research. Strides have been made in sleep-related clinical trials to include equal numbers of women; however, the inclusion of female rodents in neuroscience and sleep research is lacking. Female animals are commonly omitted from studies over concerns of the effect of estrus cycle hormones on measured outcomes. This review highlights the estrous cycle's broad effects on sleep-wake behavior: from changes in sleep macroarchitecture to regionally specific alterations in neural oscillations. These changes are largely driven by cycle-dependent ovarian hormonal fluctuations occurring during proestrus and estrus that modulate neural circuits regulating sleep-wake behavior. Removal of estrous cycle influence by ovariectomy ablates characteristic sleep changes. Further, sex differences in sleep are present between gonadally intact females and males. Removal of reproductive hormones via gonadectomy in both sexes mitigates some, but not all sex differences. We examine the extent to which reproductive hormones and sex chromosomes contribute to sex differences in sleep-wake behavior. Finally, this review addresses the limitations in our understanding of the estrous cycle's impact on sleep-wake behavior, gaps in female sleep research that are well studied in males, and the implications that ignoring the estrous cycle has on studies of sleep-related processes.

Intense Body Contact Increases Homosexual Pair Bond Stability in Female Japanese Macaques (Macaca fuscata)

The Japanese macaque (Macaca fuscata) has become a key species for studying homosexual behavior over recent decades. With the non-conceptive nature, their same-sex consortships illustrate that individual partner preferences can exist beyond direct reproductive benefits or apparent sociosexual strategies. An open question is whether the behavior shared between partners in consortship directly affects their choice to remain with a partner. With this study, we examined behavioral aspects underlying consortship temporal patterns in these promiscuous and bisexual primates. While these patterns could be relevant in both homo- and heterosexual consortships, our study primarily focused on female-female pairs. We hypothesized that the stability of consortships (duration and occurrence) is influenced by a pair's sexual behavior, mutual sexual stimulation, and close affiliative inter-mount behaviors involving high-intensity body contact. A semi-free population of Japanese macaques was observed over one mating season. In total, 40 h of focal data on female-female consortship behaviors were analyzed. Forty-six percent of all sexually mature females engaged in homosexual interactions. Our behavioral analyses of female-female pairs found that close body contact, rather than grooming or sexual interactions, was correlated with the stability of homosexual consortships. The greater the amount of huddling and embracing a pair engaged in, the more likely they were to stay together and reunite again. However, the frequency of mounting, rubbing or thrusting had no discernable effect on consortship stability. The results of this study thus add important knowledge to partner qualities in promiscuous primates as well as to inter-group differences of homosexual behavior in Japanese macaques.

Does MDMA have treatment potential in sexual dysfunction? A systematic review of outcomes across the female and male sexual response cycles

INTRODUCTION

Sexual health, an integral component of overall well-being, is frequently compromised by common yet underdiagnosed sexual dysfunctions. Traditional interventions encompass pharmaceutical and psychological treatments. Unconventional therapies, like MDMA, offer hope for sexual dysfunction. This review delves into MDMA's effects on sexual responsiveness and its potential role in treating sexual dysfunction.

OBJECTIVES

The purpose of this review is to elucidate effects of MDMA on different domains of the female and male sexual response cycles.

METHODS

We conducted a systematic review on the effects of MDMA on each domain of the female and male sexual response cycles. PubMed, MEDLINE, and EMBASE were queried, and results were screened using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Search terms utilized were "MDMA" or "ecstasy" in combination with "desire," "arousal," "lubrication," "orgasm," "pleasure," "libido," "erection," and "ejaculation." Inclusion criteria for this review were MDMA use by study subjects and sexual outcomes in at least 1 domain of the female and/or male sexual response cycles were described and measured. Randomized controlled trials, cohort studies (both prospective and retrospective), surveys, and literature reviews published between January 2000 and June 2022 were included. Case reports and studies that did not address conditions of interest were excluded from analysis. Duplicated search results were screened out. The remaining studies were then read in full text to ensure they met inclusion and exclusion criteria for analysis.

RESULTS

We identified 181 studies, of which 6 met criteria for assessment of the female sexual response cycle and 8 met criteria for assessment of the male sexual response cycle. Four of 6 studies reported increased sexual desire with MDMA use among women. Arousal and lubrication were improved with MDMA use in 3 of 4 studies, but they were not affected in 1 randomized control study. In men, 7 studies evaluated the effects of MDMA on desire and/or arousal, 5 studies measured impact on erection, 3 on orgasm, and 2 on ejaculation. Sixty percent of interview-based studies reported increased sexual desire in men, while 40% reported mixed or no effect. Two studies reported impairment of erection, 2 reported mixed effects, and 1 reported fear of erection impairment. In both men and women, all studies evaluating orgasm reported delay in achieving orgasm but increased intensity and pleasure if achieved. Primary outcome measures were variable and largely qualitative.

CONCLUSION

Our findings suggest that MDMA generally increases sexual desire and intensifies orgasm when achieved. While producing conflicting evidence on sexual arousal in both sexes, MDMA may impair erectile and ejaculatory function in men.

Early life social complexity shapes adult neural processing in the communal spiny mouse Acomys cahirinus

RATIONALE

Early life social rearing has profound consequences on offspring behavior and resilience. Yet, most studies examining early life development in rodents use species whose young are born immobile and do not produce complex social behavior until later in development. Furthermore, models of rearing under increased social complexity, rather than deprivation, are needed to provide alternative insight into the development of social neural circuitry.

OBJECTIVES

To understand precocial offspring social development, we manipulated early life social complexity in the communal spiny mouse Acomys cahirinus and assessed long-term consequences on offspring social behavior, exploration, and neural responses to novel social stimuli.

METHODS

Spiny mouse pups were raised in the presence or absence of a non-kin breeding group. Upon adulthood, subjects underwent social interaction tests, an open field test, and a novel object test. Subjects were then exposed to a novel conspecific and novel group and neural responses were quantified via immunohistochemical staining in brain regions associated with social behavior.

RESULTS

Early life social experience did not influence behavior in the test battery, but it did influence social processing. In animals exposed to non-kin during development, adult lateral septal neural responses toward a novel conspecific were weaker and hypothalamic neural responses toward a mixed-sex group were stronger.

CONCLUSIONS

Communal species may exhibit robust behavioral resilience to the early life social environment. But the early life environment can affect how novel social information is processed in the brain during adulthood, with long-term consequences that are likely to shape their behavioral trajectory.

Is Sex Good for Your Brain? A National Longitudinal Study on Sexuality and Cognitive Function among Older Adults in the United States

Using a life course approach, we examined how sexuality is related to cognitive function for partnered older adults. We utilized longitudinal data from two rounds of the National Social Life, Health, and Aging Project (NSHAP) to analyze 1,683 respondents. Cognitive function was measured using a continuous Montreal Cognitive Assessment (MoCA) score. We considered both sexual frequency and sexual quality (i.e., physical pleasure, emotional satisfaction). We estimated cross-lagged models to consider the potential reciprocal relationship between sexuality and cognitive function. Results indicated that sexuality was not related to later cognitive function in the total sample, but the pattern varied by age and gender. For adults aged 62-74, better sexual quality (i.e., feelings of physical pleasure and emotional satisfaction) was related to better cognitive functioning, while for those aged 75-90, more frequent sex was related to better cognitive functioning. Feelings of physical pleasure were related to better cognitive functioning for men but not women. There was no evidence of cognitive functioning being related to later sexuality. The findings highlight the importance of age and gender in modifying the link between sexuality and cognition in later life.

Rodent models for mood disorders - understanding molecular changes by investigating social behavior

Mood disorders, including depressive and bipolar disorders, are the group of psychiatric disorders with the highest prevalence and disease burden. However, their pathophysiology remains poorly understood. Animal models are an extremely useful tool for the investigation of molecular mechanisms underlying these disorders. For psychiatric symptom assessment in animals, a meaningful behavioral phenotype is needed. Social behaviors constitute naturally occurring complex behaviors in rodents and can therefore serve as such a phenotype, contributing to insights into disorder related molecular changes. In this narrative review, we give a fundamental overview of social behaviors in laboratory rodents, as well as their underlying neuronal mechanisms and their assessment. Relevant behavioral and molecular changes in models for mood disorders are presented and an outlook on promising future directions is given.

Gas/Liquid Chromatography-Mass Spectrometry Analysis of Key Functional Substances Regulating Poll Gland Secretion in Male Camels during Seasonal Estrus

Increased poll gland secretion is a major characteristic and indicator of estrus in male Bactrian camels; however, research on these poll glands and their secretion is extremely rare. In this study, we determine the chemical composition of poll gland secretions and identify the key functional substances that regulate seasonal estrus in male camels. A GC/LC-MS dual platform was used to analyze ventral hair (control) and neck mane samples containing poll gland secretions from male Bactrian camels during estrus. Multidimensional and single-dimensional analyses were used to screen differentially expressed metabolites (DEMs) between groups. Functional prediction of enriched metabolites was performed using a Human Metabolome Database comparison and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, which were then compared with a behavioral analysis of male Bactrian camels in estrus. A total of 1172 DEMs and 34 differential metabolic pathways were identified. One metabolite group was found to relate to steroid synthesis and metabolism, and another metabolite group was associated with neural metabolism. Therefore, we speculate that steroids and neurochemicals jointly regulate estrous behavior in male Bactrian camels, thus providing theoretical insights into the development and function of poll glands in Bactrian camels.

The endogenous cannabinoid system modulates male sexual behavior expression

The endocannabinoid system (ECS) plays a key neuromodulatory role in the brain. Main features of endocannabinoids (eCBs) are that they are produced on demand, in response to enhanced neuronal activity, act as retrograde messengers, and participate in the induction of brain plasticity processes. Sexual activity is a motivated behavior and therefore, the mesolimbic dopaminergic system (MSL) plays a central role in the control of its appetitive component (drive to engage in copulation). In turn, copulation activates mesolimbic dopamine neurons and repeated copulation produces the continuous activation of the MSL system. Sustained sexual activity leads to the achievement of sexual satiety, which main outcome is the transient transformation of sexually active male rats into sexually inhibited animals. Thus, 24 h after copulation to satiety, the sexually satiated males exhibit a decreased sexual motivation and do not respond to the presence of a sexually receptive female with sexual activity. Interestingly, blockade of cannabinoid receptor 1 (CB1R) during the copulation to satiety process, interferes with both the appearance of the long-lasting sexual inhibition and the decrease in sexual motivation in the sexually satiated males. This effect is reproduced when blocking CB1R at the ventral tegmental area evidencing the involvement of MSL eCBs in the induction of this sexual inhibitory state. Here we review the available evidence regarding the effects of cannabinoids, including exogenously administered eCBs, on male rodent sexual behavior of both sexually competent animals and rat sub populations spontaneously showing copulatory deficits, considered useful to model some human male sexual dysfunctions. We also include the effects of cannabis preparations on human male sexual activity. Finally, we review the role played by the ECS in the control of male sexual behavior expression with the aid of the sexual satiety phenomenon. Sexual satiety appears as a suitable model for the study of the relationship between eCB signaling, MSL synaptic plasticity and the modulation of male sexual motivation under physiological conditions that might be useful for the understanding of MSL functioning, eCB-mediated plasticity and their relationship with motivational processes.

Erectile Dysfunction: Treatments, Advances and New Therapeutic Strategies

Erectile dysfunction (ED) is the inability to get and maintain an adequate penile erection for satisfactory sexual intercourse. Due to its negative impacts on men's life quality and increase during aging (40% of men between 40 and 70 years), ED has always attracted researchers of different disciplines, from urology, andrology and neuropharmacology to regenerative medicine, and vascular and prosthesis implant surgery. Locally and/or centrally acting drugs are used to treat ED, e.g., phosphodiesterase 5 inhibitors (first in the list) given orally, and phentolamine, prostaglandin E1 and papaverine injected intracavernously. Preclinical data also show that dopamine D4 receptor agonists, oxytocin and α-MSH analogues may have a role in ED treatment. However, since pro-erectile drugs are given on demand and are not always efficacious, new strategies are being tested for long lasting cures of ED. These include regenerative therapies, e.g., stem cells, plasma-enriched platelets and extracorporeal shock wave treatments to cure damaged erectile tissues. Although fascinating, these therapies are laborious, expensive and not easily reproducible. This leaves old vacuum erection devices and penile prostheses as the only way to get an artificial erection and sexual intercourse with intractable ED, with penile prosthesis used only by accurately selected patients.

Evolutionary and neuroendocrine foundations of human aggression

Humans present a behavioural paradox: they are peaceful in many circumstances, but they are also violent and kill conspecifics at high rates. We describe a social evolutionary theory to resolve this paradox. The theory interprets human aggression as a combination of low propensities for reactive aggression and coercive behaviour and high propensities for some forms of proactive aggression (especially coalitionary proactive aggression). These tendencies are associated with the evolution of groupishness, self-domestication, and social norms. This human aggression profile is expected to demand substantial plasticity in the evolved biological mechanisms responsible for aggression. We discuss the contributions of various social signalling molecules (testosterone, cortisol, oxytocin, vasopressin, serotonin, and dopamine) as the neuroendocrine foundation conferring such plasticity.

Crosstalk between the endocannabinoid and mid-brain dopaminergic systems: Implication in dopamine dysregulation

Endocannabinoids (eCBs) and the expanded endocannabinoid system (ECS)-"endocannabinoidome", consists of the endogenous ligands, eCBs, their canonical and non-canonical receptor subtypes, and their synthesizing and metabolizing enzymes. This system modulates a wide range of body functions and acts as a retrograde signaling system within the central nervous system (CNS) by inhibition of classical transmitters, and plays a vital modulatory function on dopamine, a major neurotransmitter in the CNS. Dopamine is involved in different behavioral processes and contributes to different brain disorders-including Parkinson's disease, schizophrenia, and drug addiction. After synthesis in the neuronal cytosol, dopamine is packaged into synaptic vesicles until released by extracellular signals. Calcium dependent neuronal activation results in the vesicular release of dopamine and interacts with different neurotransmitter systems. The ECS, among others, is involved in the regulation of dopamine release and the interaction occurs either through direct or indirect mechanisms. The cross-talk between the ECS and the dopaminergic system has important influence in various dopamine-related neurobiological and pathologic conditions and investigating this interaction might help identify therapeutic targets and options in disorders of the CNS associated with dopamine dysregulation.

Trade-off between pre and post-copulatory traits depends on locomotor activity in male Tribolium castaneum beetles

Locomotor performance is an indicator of dynamic exercise; thus, it is a central trait in many animal behaviours. Although higher locomotor endurance may increase male reproductive success (e.g., in mate searching and male-male contests), investment in other male reproductive traits (e.g., male attractiveness and sperm competition) may be decreased through energy consumption due to higher activity levels. Here, I investigated male attractiveness, mating success, and paternity success using males of the red flour beetle Tribolium castaneum selected for higher (H) and lower (L) locomotor endurance. Although there was no difference in male attractiveness between the selection regimes, H males had significantly higher mating success than L males. Conversely, L males had significantly higher paternity success than H males. Therefore, there was a trade-off between mating success and paternity success among the selection regimes, suggesting that locomotor endurance affects male reproduction in T. castaneum, and individual variation of locomotor endurance may be maintained within a population.

The nucleus accumbens dopamine increase, typically triggered by sexual stimuli in male rats, is no longer produced when animals are sexually inhibited due to sexual satiety

RATIONALE

Exposure of male rats to an inaccessible receptive female and copulation increases dopamine (DA) levels in the nucleus accumbens (NAcc). Males copulating to satiety become sexually inhibited and most of them do not display sexual activity when presented with a sexually receptive female 24 h later. This inhibitory state can be pharmacologically reversed. There are no studies exploring NAcc DA levels during this sexual inhibitory state.

OBJECTIVES

To characterize changes in NAcc DA and its metabolites' levels during sexual satiety development, during the well-established sexual inhibitory state 24 h later, and during its pharmacological reversal.

METHODS

Changes in NAcc DA and its metabolites were measured in sexually experienced male rats, using in vivo microdialysis, during copulation to satiety, when presented to a new sexually receptive female 24 h later, and during the pharmacological reversal of the sexual inhibition by anandamide.

RESULTS

NAcc DA levels remained increased during copulation to satiety. DA basal levels were significantly reduced 24 h after copulation to satiety, as compared to the initial basal levels. Presenting a receptive female behind a barrier 24 h after satiety did not induce the typical NAcc DA elevation in the sexually satiated males but there was a decrease that persisted when they got access to the female, with which they did not copulate. Anandamide injection slightly increased NAcc DA levels coinciding with sexual satiety reversal.

CONCLUSIONS

Reduced NAcc DA concentrations coincide with the inhibition of an instinctive, natural rewarding behavior suggesting that there might be a DA concentration threshold needed to be responsive to a rewarding stimulus.

Behavioral, Neural, and Molecular Mechanisms of Conditioned Mate Preference: The Role of Opioids and First Experiences of Sexual Reward

Although mechanisms of mate preference are thought to be relatively hard-wired, experience with appetitive and consummatory sexual reward has been shown to condition preferences for partner related cues and even objects that predict sexual reward. Here, we reviewed evidence from laboratory species and humans on sexually conditioned place, partner, and ejaculatory preferences in males and females, as well as the neurochemical, molecular, and epigenetic mechanisms putatively responsible. From a comprehensive review of the available data, we concluded that opioid transmission at μ opioid receptors forms the basis of sexual pleasure and reward, which then sensitizes dopamine, oxytocin, and vasopressin systems responsible for attention, arousal, and bonding, leading to cortical activation that creates awareness of attraction and desire. First experiences with sexual reward states follow a pattern of sexual imprinting, during which partner- and/or object-related cues become crystallized by conditioning into idiosyncratic "types" that are found sexually attractive and arousing. These mechanisms tie reward and reproduction together, blending proximate and ultimate causality in the maintenance of variability within a species.

Dopamine, Erectile Function and Male Sexual Behavior from the Past to the Present: A Review

Early and recent studies show that dopamine through its neuronal systems and receptor subtypes plays different roles in the control of male sexual behavior. These studies show that (i) the mesolimbic/mesocortical dopaminergic system plays a key role in the preparatory phase of sexual behavior, e.g., in sexual arousal, motivation and reward, whereas the nigrostriatal system controls the sensory-motor coordination necessary for copulation, (ii) the incertohypothalamic system is involved in the consummatory aspects of sexual behavior (penile erection and copulation), but evidence for its role in sexual motivation is also available, (iii) the pro-sexual effects of dopamine occur in concert with neural systems interconnecting the hypothalamus and preoptic area with the spinal cord, ventral tegmental area and other limbic brain areas and (iv) D₂ and D₄ receptors play a major role in the pro-sexual effects of dopamine. Despite some controversy, increases or decreases, respectively, of brain dopamine activity induced by drugs or that occur physiologically, usually improves or worsens, respectively, sexual activity. These findings suggest that an altered central dopaminergic tone plays a role in mental pathologies characterized by aberrant sexual behavior, and that pro-erectile D₄ receptor agonists may be considered a new strategy for the treatment of erectile dysfunction in men.

Mechanistic analysis of erectile dysfunction in a depression rat model

Objective

Most men suffering from depression have different degrees of erectile dysfunction (ED), but the relationship between depression and ED is not clear. This study explored the effect of depression on erectile function in rats and the underlying mechanism.

Methods

The potential targets and key signaling pathways of depression and ED were predicted through bioinformatics analysis, and a depression rat model was established by inducing chronic restraint stress. Pathological changes in rat penis tissue were studied by hematoxylin and eosin staining. The serum dopamine level was quantified by an enzyme-linked immunosorbent assay. The expression of related proteins and mRNA was detected by western blotting and real-time quantitative reverse transcription-polymerase chain reaction.

Results

Hematoxylin and eosin staining showed pathological damage in the penile tissue of the model group rats. The serum dopamine level, dopamine receptor D2 (DRD2) and solute carrier family 6 member 3 (SLC6A3) protein levels in penile tissue, and DRD2 and SLC6A3 mRNA levels were lower in the model group than in the control group.

Conclusion

The decrease in erectile function in the depression rat model was related to dysfunction of the dopamine system and dopaminergic synapse signaling pathway.

Pharmacological strategies for sexual recovery in men undergoing antipsychotic treatment

INTRODUCTION

: First- and second-generation antipsychotics are highly accountable for causing a plethora of medical side effects, ranging from metabolic imbalances to sexual dysfunction (SD), that frequently undermine patient-doctor relationships. Nevertheless, to date antipsychotics are one of the best treatment options for dealing with numerous either acute or chronic conditions like agitation, suicidality, depression, dementia, and of course psychosis. For these reasons, clinicians need to handle them wisely to preserve patients' sexual health, avoid poor therapeutic adherence and prevent high rates of therapy drop-out.

AREAS COVERED

: This article reviews the literature on pharmacologic approaches for management strategies in men who are administered with antipsychotics and developed SD. The etiology of antipsychotic-induced SD is also discussed.

EXPERT OPINION

: Clinicians must consider sexual life as a major health domain. To do so, a first step would be to measure and monitor sexual function by means of psychometric tools. Secondly, primary prevention should be conducted when choosing antipsychotics, i.e., picking sex-sparing compounds like aripiprazole or brexpiprazole. Thirdly, if sexolytic compounds cannot be dismissed, such as first-generation antipsychotics, risperidone, paliperidone, or amisulpride, then aripiprazole 5-20 mg/day adjunctive therapy has proven to be most effective in normalizing prolactin levels and consequently treating antipsychotic-induced SD.

Microplastics and Their Impact on Reproduction-Can we Learn From the C. elegans Model?

Biologically active environmental pollutants have significant impact on ecosystems, wildlife, and human health. Microplastic (MP) and nanoplastic (NP) particles are pollutants that are present in the terrestrial and aquatic ecosystems at virtually every level of the food chain. Moreover, recently, airborne microplastic particles have been shown to reach and potentially damage respiratory systems. Microplastics and nanoplastics have been shown to cause increased oxidative stress, inflammation, altered metabolism leading to cellular damage, which ultimately affects tissue and organismal homeostasis in numerous animal species and human cells. However, the full impact of these plastic particles on living organisms is not completely understood. The ability of MPs/NPs to carry contaminants, toxic chemicals, pesticides, and bioactive compounds, such as endocrine disrupting chemicals, present an additional risk to animal and human health. This review will discusses the current knowledge on pathways by which microplastic and nanoplastic particles impact reproduction and reproductive behaviors from the level of the whole organism down to plastics-induced cellular defects, while also identifying gaps in current knowledge regarding mechanisms of action. Furthermore, we suggest that the nematode Caenorhabditis elegans provides an advantageous high-throughput model system for determining the effect of plastic particles on animal reproduction, using reproductive behavioral end points and cellular readouts.

The interaction between sexual reward/ deprivation and the acquisition, extinction and reinstatement of morphine-seeking behavior

Natural rewards and abused drugs affect the function of the common brain's reward system. Interaction between social and drug rewards can change the vulnerability to development of drug addiction. Here, we investigate the effects of sexual experience and sex deprivation on the acquisition, maintenance, and drug prime-induced reinstatement of morphine-seeking behavior in male mice using conditioned place preference (CPP). CPP induced with morphine (3, 5, 7 mg/kg, s.c. for 3 days) lasted for 10 days after cessation of morphine treatment and priming dose of morphine (2 mg/kg, s.c.) reinstated the extinguished CPP. In the post-test phase, sexually experienced animals showed a lower preference for morphine compared to sex-deprived males. In the extinction phase, sex deprivation shortened maintenance time compared to control animals. The preference for morphine in sexually experienced animals did not diminish by the seventeenth extinction day. In both groups, the priming injection of morphine after the extinction period could reinstate the extinguished morphine-induced CPP. Together, these data showed the interaction between sex and drug reward and that sexual behavior -a natural rewarding stimulus- can prolong, whereas sex deprivation can block the maintenance of morphine-seeking behaviors. Sexual experience may induce functional and morphological alterations in brain reward areas particularly the mesolimbic system similar to repeated exposure to abused drugs which can affect morphine-seeking behaviors.

Gene expression in the amygdala and hippocampus of cyclic and acyclic gilts

Age at first estrus is the earliest phenotypic indicator of future reproductive success of gilts. Prebreeding anestrus is a major reason for reproductive failure leading to culling of replacement gilts. The two types of prebreeding anestrus are delay in attaining puberty (prepubertal anestrus, PPA) and silent ovulation (behavioral anestrus, BA). Neural tissues such as amygdala and hippocampus play a major role in regulating sexual behavior, social interactions, and receptivity to males. Differences in gene expression in the amygdala and hippocampus of gilts were analyzed in three comparisons: 1) PPA cases and cyclic controls at follicular phase of estrous cycle, 2) BA cases and cyclic controls at luteal phase of estrous cycle, and 3) gilts at different stages of the ovarian cycle (cyclic gilts at follicular phase and luteal phase of estrous cycle) to gain functional understanding of how these rarely studied tissues may differ between pubertal phenotypes and different stages of the estrous cycle of gilts. Differentially expressed genes (DEG) between PPA and BA cases and their respective cyclic controls were involved in neurological and behavioral disorders as well as nervous system functions that could directly or indirectly involved in development of behaviors related to estrus. The comparison between cyclic follicular and luteal phase control gilts identified the greatest number of DEG in the hippocampus and amygdala. These DEG were involved in adult neurogenesis and neural synapse (e.g., GABAergic, dopamine, cholinergic), suggesting that these tissues undergo structural changes and synaptic plasticity in gilts. This is the first report to demonstrate that the stage of estrous cycle is associated with dynamic changes in gene expression within porcine hippocampus and amygdala and indicates a role of gonadal steroids in regulating their biology.

Sexual Dysfunction Among Patients With Chronic Kidney Disease

Sexual dysfunction (SD) in patients with chronic kidney disease is common and negatively impacts quality of life. SD is often under-appreciated because of overall low awareness. Diagnosis of SD is subjective, and manifestations can be different among men and women. Causes of SD are multifactorial, including psychological disorders, hormonal imbalances, vascular disorders, neurological disorders, and medication side effects. Non-specific approaches to improving sexual function include addressing underlying psychological disorders, promoting lifestyle modifications, optimizing dialysis care, and facilitating successful kidney transplantation, whereas treatment with phosphodiesterase type 5 inhibitor, hormone replacement, and mechanical devices can be offered to patients with specific indications.

Evolutionary insights into sexual behavior from whiptail lizards

Is the brain bipotential or is sex-typical behavior determined during development? Thirty years of research in whiptail lizards transformed the field of behavioral neuroscience to show the brain is indeed bipotential, producing behaviors along a spectrum of male-typical and female-typical behavior via a parliamentary system of neural networks and not a predetermined program of constrained behavioral output. The unusual clade of whiptail lizards gave these insights as there are several parthenogenetic all-female species that display both male-typical and female-typical sexual behavior. These descendant species exist alongside their ancestors, allowing a unique perspective into how brain-behavior relationships evolve. In this review, we celebrate the over 40-year career of David Crews, beginning with the story of how he established whiptails as a model system through serendipitous behavioral observations and ending with advice to young scientists formulating their own questions. In between these personal notes, we discuss the discoveries that integrated hormones, neural activity, and gene expression to provide transformative insights into how brains function and reshaped our understanding of sexuality.

The Brain's Reward System in Health and Disease

Rhythmic gene expression is found throughout the central nervous system. This harmonized regulation can be dependent on- and independent of- the master regulator of biological clocks, the suprachiasmatic nucleus (SCN). Substantial oscillatory activity in the brain's reward system is regulated by dopamine. While light serves as a primary time-giver (zeitgeber) of physiological clocks and synchronizes biological rhythms in 24-h cycles, nonphotic stimuli have a profound influence over circadian biology. Indeed, reward-related activities (e.g., feeding, exercise, sex, substance use, and social interactions), which lead to an elevated level of dopamine, alters rhythms in the SCN and the brain's reward system. In this chapter, we will discuss the influence of the dopaminergic reward pathways on circadian system and the implication of this interplay on human health.

Oxytocin induces lordosis behavior in female rats through the prostaglandin E2/GnRH signaling system

Intracerebroventricular (icv) administration of oxytocin (OT) induces robust lordosis behavior (lordosis quotient and lordosis intensity) in estrogen-primed rats. The present study explored the hypothesis that the OT-Prostaglandin E2-GnRH pathway (a pathway produced in astrocytes) is involved in the facilitation of lordosis behavior by icv infusion of OT (2 μg). In Experiment 1, we tested the involvement of the OT receptor (OTR) by infusion of the OTR antagonist, atosiban (ATO). OT-induced lordosis was significantly reduced at both 30 and 120 min by prior infusion of ATO. In Experiment 2, we studied the effects of aspirin (COX2 inhibitor) and ONO-AE3-208 (ONO; EP4 prostaglandin receptor antagonist) on OT-induced lordosis. Infusions of both compounds diminished OT-induced lordosis at both 120 and 240 min. In Experiment 3, the involvement of the GnRH-1 receptor inhibitor antide on OT-induced lordosis was evaluated. Antide significantly inhibited OT-induced lordosis at all times tested. These data indicate that the OT/PGE2/GnRH pathway is involved in the expression of OT-induced lordosis behavior, an effect that may be occurring directly in hypothalamic astrocytes.

Effect of Moringa oleifera Lam. Leaf Tea on Sexual Behavior and Reproductive Function in Male Rats

Moringa oleifera Lam. (M. oleifera) has been called the "miracle tree" due to its attributes for therapy in various diseases. However, M. oleifera studies on the male reproductive system have been limited. The aim of this study was a phytochemical screening and investigation of the effects of M. oleifera leaf tea on sexual behavior, reproductive function and antioxidant activities. Male rats were fed with M. oleifera leaf tea extract at doses of 0.55, 1.10 and 2.20 mg/kg or distilled water for 30 days. The result showed that M. oleifera leaf tea contained rich total phenols and flavonoids. The courtship behavior, seminiferous tubule diameter, epithelium height, epithelium area, type A spermatogonia, and spermatogonia efficiency were significantly increased in all treatment groups. The groups treated with 1.10 and 2.20 mg/kg increased the number of Sertoli cells. The total of spermatogenic cells increased in the group treated with 0.55 mg/kg. M. oleifera leaf tea scavenged DPPH radical, ABTS radical and H₂O₂, and inhibited LPO and AGEs formation. Due to M. oleifera leaf tea containing rich total phenols, flavonoids, and antioxidants, it could enhance sexual function and the male reproductive system.

Endocannabinoids Released in the Ventral Tegmental Area During Copulation to Satiety Modulate Changes in Glutamate Receptors Associated With Synaptic Plasticity Processes

Endocannabinoids modulate mesolimbic (MSL) dopamine (DA) neurons firing at the ventral tegmental area (VTA). These neurons are activated by copulation, increasing DA release in nucleus accumbens (NAcc). Copulation to satiety in male rats implies repeated ejaculation within a short period (around 2.5 h), during which NAcc dopamine concentrations remain elevated, suggesting continuous neuronal activation. During the 72 h that follow copulation to satiety, males exhibit long-lasting changes suggestive of brain plasticity processes. Enhanced DA neuron activity triggers the synthesis and release of endocannabinoids (eCBs) in the VTA, which participate in several long-term synaptic plasticity processes. Blockade of cannabinoid type 1 receptors (CB1Rs) during copulation to satiety interferes with the appearance of the plastic changes. Glutamatergic inputs to the VTA express CB1Rs and contribute to DA neuron burst firing and synaptic plasticity. We hypothesized that eCBs, released during copulation to satiety, would activate VTA CB1Rs and modulate synaptic plasticity processes involving glutamatergic transmission. To test this hypothesis, we determined changes in VTA CB1R density, phosphorylation, and internalization in rats that copulated to satiety 24 h earlier as compared both to animals that ejaculated only once and to sexually experienced unmated males. Changes in glutamate AMPAR and NMDAR densities and subunit composition and in ERK1/2 activation were determined in the VTA of males that copulated to satiety in the presence or absence of AM251, a CB1R antagonist. The CB1R density decreased and the proportion of phosphorylated CB1Rs increased in the animals that copulated compared to control rats. The CB1R internalization was detected only in sexually satiated males. A decrease in α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor (AMPAR) density, blocked by AM251 pretreatment, and an increase in the proportion of GluA2-AMPARs occurred in sexually satiated rats. GluN2A- N-methyl-D-aspartate receptor (NMDAR) expression decreased, and GluN2B-NMDARs increased in these animals, both of which were prevented by AM251 pre-treatment. An increase in phosphorylated ERK1/2 emerged in males copulating to satiety in the presence of AM251. Results demonstrate that during copulation to satiety, eCBs activate CB1Rs in the VTA, producing changes in glutamate receptors compatible with a reduced neuronal activation. These changes could play a role in the induction of the long-lasting physiological changes that characterize sexually satiated rats.

Paternal exposure to a common pharmaceutical (Ritalin) has transgenerational effects on the behaviour of Trinidadian guppies

Evidence is emerging that paternal effects, the nongenetic influence of fathers on their offspring, can be transgenerational, spanning several generations. Methylphenidate hydrochloride (MPH; e.g. Ritalin) is a dopaminergic drug that is highly prescribed to adolescent males for the treatment of Attention-deficit/hyperactivity disorder. It has been suggested that MPH could cause transgenerational effects because MPH can affect the male germline in rodents and because paternal effects have been observed in individuals taking similar drugs (e.g. cocaine). Despite these concerns, the transgenerational effects of paternal MPH exposure are unknown. Therefore, we exposed male and female Trinidadian guppies (Poecilia reticulata) to a low, chronic dose of MPH and observed that MPH affected the anxiety/exploratory behaviour of males, but not females. Because of this male-specific effect, we investigated the transgenerational effects of MPH through the paternal line. We observed behavioural effects of paternal MPH exposure on offspring and great-grandoffspring that were not directly administered the drug, making this the first study to demonstrate that paternal MPH exposure can affect descendants. These effects were not due to differential mortality or fecundity between control and MPH lines. These results highlight the transgenerational potential of MPH.

Cybersex addiction in a gay man: a case report

BACKGROUND

Cybersex addiction is a sexual addiction characterized by virtual Internet sexual activity that causes serious negative consequences to one's physical, mental, social, and/or financial well-being. Previous studies have mostly addressed cybersex addiction in heterosexual males.

PURPOSE

To describe a case report of a 26-year-old gay man suffering from a cybersex addiction.

METHODS

We use Griffiths' model of the common components of addictions.

RESULTS

We reveal this case report of cybersex addiction possesses all of six components universal for addictions.

CONCLUSIONS

In light of the increasing prevalence of various behavioral addictions (especially, Internet addictions), clinical psychiatrists should be aware of the cybersex addiction phenomenon.

Experimentally altered male mating behaviour affects offspring exploratory behaviour via nongenetic paternal effects

Evidence is emerging that fathers can have nongenetic effects on the phenotypes of their offspring. Most studies have focused on the role that nongenetic modifications to sperm can have on offspring phenotype; however, fathers can also have nongenetic effects on offspring through their interactions with females, called female-mediated paternal effects. These effects can occur in situations where male phenotype, e.g. behaviour or morphology, affects female stress and/or provisioning of offspring. These effects are potentially widespread, but few studies have explicitly investigated the role of female-mediated paternal effects on offspring phenotype. Here, we asked if male mating interactions can affect offspring via female mediated paternal effects in the Trinidadian guppy, Poecilia reticulata. To do this, we manipulated mating behaviour by: (i) administering a drug known to affect the neurotransmitter dopamine, and (ii) varying the familiarity of potential mates, which affects attractiveness in this species. With these treatments, we successfully manipulated the mating behaviour of male guppies and female preference for those males. Further, we found significant effects of sire mating behaviour, sire drug treatment, and parental familiarity status on behavioural measures of offspring anxiety in response to a novel object. Because Control offspring of 'familiar' and 'unfamiliar' pairs differed in their behaviour, our results cannot be solely attributed to potential nongenetic modifications to sperm caused by the drug. These results emphasize the importance of female-mediated paternal effects, including those caused by altered male mating behaviour, in shaping offspring phenotype.

Spontaneous Ejaculation: A Focused Review for the Clinicians

INTRODUCTION

The process of ejaculation has important meanings not only for its association with orgasm but also for the timing to ejaculate in the context of sexual activity. Spontaneous (involuntary) ejaculation (SE) without any sexual stimulation is a distressing symptom. Our understanding of SE is limited. Unfortunately, many physicians are not aware of these cases.

OBJECTIVES

The objective of this study is to describe the etiopathogenesis, clinical features, diagnosis, and treatment options for SE.

METHODS

We searched the literature for publications on "SE," "spontaneous emission" or "involuntary ejaculation," and factors influencing SE in the PUBMED/MEDLINE, Scopus, Cochrane Library, EMBASE, PsycINFO, ProQuest, Academic Search Complete database, Google Scholar, and CINAHL databases from inception to August 2020.

RESULTS

The literature search yielded 36 relevant publications reporting on 43 patients with SE. Attempts to explain the cause of pathologic SE have included 4 etiological groups (spinal cord lesions, psychological causes, rabies, and drug-induced). The underlying mechanisms responsible for induction of SE may include increased adrenergic activity, overactivity in dopaminergic system, decreased serotonergic activity, damage of descending inhibitory pathway, or penile hyperexcitability. SE may occur in the absence of an identifiable trigger or may be triggered by non-sexual circumstances (micturition, defecation, glans touch, anxiety, panic attack, or school examinations). Treatment options include psychoanalytic treatment, paroxetine, citalopram, sertraline, silodosin, and anxiolytics. In drug-induced SE, dose reduction and drug withdrawal with or without switching to another drug may relief SE.

CONCLUSIONS

SE is one of the least reported ejaculatory dysfunction. The key feature shared in common by these men is SE without any sexual thoughts or fantasies, may be triggered by non-sexual contexts, rarely associated with orgasm or erection. Treatment by psychoanalytic treatment and pharmacotherapy may be helpful. Further research might explore the definite underlying mechanisms. Abdel-Hamid IA, Ali OI. Spontaneous Ejaculation: A Focused Review for the Clinicians. Sex Med Rev 2021;9:406-422.

Hypothalamic Monoaminergic Pathology in a Neurodevelopmental Rat Model Showing Prenatal 5-Bromo-2'-Deoxyuridine Treatment-Induced Hyperactivity and Hyporeproductivity

OBJECTIVE

Prenatal treatment of rats with 5-bromo-2'-deoxyuridine (BrdU) is a neurodevelopmental model showing hyperactivity and impaired sexual activity. Human neurodevelopmental disorders, such as autism, exhibit sex-related pathology, but sex-related neurodevelopment has not been fully investigated in this model. We conducted this study to facilitate the understanding of the pathophysiology of neurodevelopmental disorders.

METHODS

Pregnant rats received 50 mg/kg BrdU on gestational days 9-15. The tissue content of dopamine (DA), serotonin (5-HT), and their metabolites dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid were measured in male and female offspring at 3 weeks (juveniles) and 10 weeks (adults) of age.

RESULTS

Prenatally BrdU-treated rats had reduced DA metabolism or DA content in the hypothalamus from the juvenile through the adult period without sex differences, but sex-specific striatal DA abnormalities emerged after maturation. A reduction in 5-HT metabolism was measured in the hypothalamus without sex differences throughout development. Developmental alterations in the striatal 5-HT states were sex-dependent. Temporal changes in DA or 5-HT metabolism were found in the frontal cortex and midbrain.

CONCLUSION

The sex-specific influence of a genotoxic factor on the development of the DA and 5-HT systems was clarified in the hypothalamus and striatum. The results suggest that the observed sex dependence and region specificity are related to the pathology of social dysfunction in neurodevelopmental disorders.

Low-frequency electroacupuncture at acupoints guanyuan (CV4) and zhongji (CV3) lengthen ejaculatory latency and improves sexual behavior in male rats

Acupuncture is a key component of Traditional Chinese Medicine in which needles are inserted into specific areas in the body to stimulate certain physiological reactions of the body. Clinical research shows that acupuncture is beneficial in treating a variety of illnesses, such as erectile dysfunction. Therefore, we investigated the effect of electroacupuncture (EA) stimulation of both low- and high frequencies at Guanyuan (CV4) and Zhongji (CV3) acupoints on male copulatory behavior in sexually experienced male rats. The animals were randomly divided into four groups: control, sham EA, EA, and only acupuncture. The administered low and high EA were 2 Hz and 80 Hz, respectively, for which the respective intensities were 1.5 mA (30 min/day for 5 days) and 1.5 mA (30 min once). The only acupuncture-administered group received acupunctures at CV4 and CV3 without electrical stimulation. Following the acupuncture treatments, copulatory behavior test was conducted. Eventually, animals were sacrificed and blood samples were collected for testing the serum hormonal profile including luteinizing hormone (LH), testosterone (T), and serotonin (5-HT). Results showed that low-frequency EA-treated rats exhibited increasing intromissions and ejaculation latency compared to control, sham EA, and acupuncture groups, while high-frequency EA-treated rats displayed lower intromissions and ejaculation frequency when compared with those in controls. Furthermore, serum levels of 5-HT and LH in low-frequency EA-treated rats were higher than all the other groups. These results indicate that compared to high-frequency EA, the low-frequency EA might be efficacious in the treatment of premature ejaculation, thereby improving sexual behavior.

Protective Effect of Vitamin C and Zinc as an Antioxidant Against Chemotherapy-Induced Male Reproductive Toxicity

Treatment with anticancer drugs such as cyclophosphamide can harm the male reproductive system. Vitamin C and zinc are micronutrients with antioxidant activity and are the essential components of semen. Therefore, this study aimed to evaluate whether cyclophosphamide-exposed mice can recover from fertility with vitamin C and zinc therapy.

In this experimental study, fifty male mice were divided into five groups. Groups 1-4 received cyclophosphamide (100 mg/kg, once a week for eight weeks). Also, group 2 received zinc (200 mg/kg), group 3 received vitamin C (300 mg/kg), group 4 received zinc and vitamin C (200 mg/kg and 300 mg/kg, respectively), five times per week for eight weeks, and group 5 received normal saline once a week and water five days a week for eight weeks. The data collected were statistically analyzed using SPSS 22.

Results showed a significant increase in mount latency and a significant decrease in the number of sperms in the cyclophosphamide group compared to the control group. However, mount latency has been significantly decreased in mice treated with cyclophosphamide plus zinc compared to the cyclophosphamide group. The study also showed that the sperm count in the group that received cyclophosphamide and zinc had been increased compared to the cyclophosphamide group; the other treatments have decreased mount latency and increased the sperm count compared to the group treated with cyclophosphamide but not significantly. The Tubule Differentiation Index showed an increase in the cyclophosphamide-Zinc-Vitamin C group in comparison with the cyclophosphamide group.

The current study showed that zinc could improve cyclophosphamide-induced toxicity of the reproductive system in male mice.

Effects of Inactivation of the Periaqueductal Gray on Song Production in Testosterone-Treated Male Canaries (Serinus canaria)

Male canaries (Serinus canaria) display seasonal changes in the motivation to sing which have been found to be dependent on the action of testosterone (T). During the breeding season when T is high, males sing at a higher rate compared with males with low T. The effect of T on song rate is known to be mediated by the medial preoptic nucleus (POM); however, it is unclear how T signaling in POM impacts song production. One potential mechanism is via modulation of dopaminergic input into song control nuclei by the periaqueductal gray (PAG). In order to test the role of PAG in T-mediated song production, we treated male canaries with peripheral T implants and implanted a guide cannula targeting the PAG. Through this guide cannula, we transiently inactivated PAG with injections of the GABA_A agonist, muscimol. Each bird received multiple infusions of both muscimol and saline with a 48-h washout period between treatments. The order of injection type was randomized and counterbalanced between individuals. Muscimol infusion into the PAG, but not nearby regions, increased the latency to sing post-injection. These results support the hypothesis that PAG is involved in the production of song, potentially mediating the motivation to sing or alternatively interfering with the pre-motor activity of nucleus RA. Other song features were however not affected.

Changes in sexual behavior patterns due to stimulants use: three case reports

The paper describes three case reports of changes in sexual behavior patterns in male patients who use stimulants (amphetamine and mephedrone). Two of them demonstrate that the consumption of stimulants may lead to hypersexuality and excessive masturbation. Case report three shows that mephedrone use results in such typical stimulant-related subjective effects as the intensification of sensory experiences and sexual arousal. It leads to the loss of interest in sex without mephedrone. In light of the popularity of sex under the influence of drugs, clinicians should be aware of this phenomenon, since it is associated with high-risk sexual behavior. The description of clinical cases on the link between sex and drugs expands our knowledge in this area, leading to more effective treatment interventions.

Altered Sexual Behavior in Dopamine Transporter (DAT) Knockout Male Rats: A Behavioral, Neurochemical and Intracerebral Microdialysis Study

Central dopamine plays a key role in sexual behavior. Recently, a Dopamine Transporter knockout (DAT KO) rat has been developed, which displays several behavioral dysfunctions that have been related to increased extracellular dopamine levels and altered dopamine turnover secondary to DAT gene silencing. This prompted us to characterize the sexual behavior of these DAT KO rats and their heterozygote (HET) and wild type (WT) counterparts in classical copulatory tests with a sexually receptive female rat and to verify if and how the acquisition of sexual experience changes along five copulatory tests in these rat lines. Extracellular dopamine and glutamic acid concentrations were also measured in the dialysate obtained by intracerebral microdialysis from the nucleus accumbens (Acb) shell of DAT KO, HET and WT rats, which underwent five copulatory tests, when put in the presence of an inaccessible sexually receptive female rat and when copulation was allowed. Markers of neurotropism (BDNF, trkB), neural activation (Δ-FosB), functional (Arc and PSA-NCAM) and structural synaptic plasticity (synaptophysin, syntaxin-3, PSD-95) were also measured in the ventral tegmental area (VTA), Acb (shell and core) and medial prefrontal cortex (mPFC) by Western Blot assays. The results indicate that the sexual behavior of DAT KO vs. HET and WT rats shows peculiar differences, mainly due to a more rapid acquisition of stable sexual activity levels and to higher levels of sexual motivation and activity. These differences occurred with differential changes in dopamine and glutamic acid concentrations in Acb dialysates during sexual behavior, with lower increases of dopamine and glutamic acid in DAT KO vs. WT and HET rats, and a lower expression of the markers investigated, mainly in the mPFC, in DAT KO vs. WT rats. Together these findings confirm a key role of dopamine in sexual behavior and provide evidence that the permanently high levels of dopamine triggered by DAT gene silencing cause alterations in both the frontocortical glutamatergic neurons projecting to the Acb and VTA and in the mesolimbic dopaminergic neurons, leading to specific brain regional changes in trophic support and neuroplastic processes, which may have a role in the sexual behavior differences found among the three rat genotypes.

Dysthymia and depressive disorders: dopamine hypothesis

This paper reviews the recent literature supporting the hypothesis that reduced neurotransmission in the mesolimbic dopamine (DA) system may sustain some of the symptoms of depressive conditions including dysthymia. Experimental evidences indicate that mesolimbic DA plays a crucial role in controlling incentive, motivation and reward. Additionally, in different models of depression, a reduced DA activity in the limbic system, reversed by chronic antidepressant treatment, is observed. Finally, different antidepressants, irrespective of their acute action on the uptake of norepinephrine or serotonin, have the common property when given chronically to potentiate behavioural responses to DA agonists. The DA hypothesis of depression offers an explanation for the antidepressive effect of drugs such as sulpiride and amisulpride given at low doses, that preferentially block DA autoreceptors and thereby increase DA output.

Sexual Expression and Cognitive Function: Gender-Divergent Associations in Older Adults

Prior research demonstrates a positive association between sexual activity and cognitive function in later life. However, the relationship between the type of sexual activity and cognitive function in older adulthood remains unclear. This study explored the associations between the frequency of engaging in different types of sexual activities (intercourse, masturbation, and kissing/petting/fondling) and cognitive function in older women and men. Using data from Wave 6 of the English Longitudinal Study of Aging (ELSA), 1915 women and 2195 men (age range 50-89 years; n = 4110) reporting any type of sexual activity over the past 12 months were included in the study. Multiple regression controlling for age, education, satisfaction with sex life, cohabiting, wealth, general health, physical activity, depression, and loneliness was used to explore the associations between the frequency of engagement in intercourse, masturbation, and kissing/petting/fondling, and two measures of cognitive function: word recall and number sequencing. For women, masturbation was linked to better word recall (p = .008), while for men, kissing/petting/fondling was associated with better number sequencing (p = .035). In women (p = .016) and men (p = .018), dissatisfaction with sex life was associated with better number sequencing. The results point to gendered links between sexual activity and cognitive function. These gender-related divergences may reflect differences in biological/neurological mechanisms, or in cognitive lifestyle factors that could influence cognitive reserve in later life. This novel study underscores the need to delineate the underlying mechanisms of the association between sex and cognition in men and women.

Sexual activity and cognitive decline in older age: a prospective cohort study

BACKGROUND

To explore the association between sexual activity and change in cognitive function over 4 years in a representative sample of older adults in England.

METHODS

Data were from 1963 men and 2513 women participating in Wave 6 (2012/2013) and Wave 8 (2016/2017) of the English Longitudinal Study of Ageing. Participants reported whether or not they had engaged in any sexual activity in the last year. Cognitive function was assessed with tests of immediate and delayed recall. Adjusted general linear models were used to test associations between sexual activity and changes in cognitive function.

RESULTS

Men who were sexually active at baseline had better preservation in immediate (0.18 points, 95% CI 0.07-0.29, p = 0.002) and delayed recall (0.19 points, 95% CI 0.08-0.29, p = 0.001) over 4-year follow-up. No significant associations were observed for women.

DISCUSSION

Strengths of this study include large, representative sample, longitudinal design and adjustment for a wide range of potential confounders. The observational nature of our study means we cannot deduce the exact direction of effect of our findings. In addition, cognitive ability test scores in older people may reflect not only a possible decline, but also their peak prior cognitive ability; but we did not have any information regarding the trajectories of their cognitive function during the lifespan.

CONCLUSION

Health practitioners should be encouraged to screen older men relating to their sexual activity to identify those who may be at risk of cognitive decline. Older men will be heartened to know that sexual activity may aid in the prevention of age-related decline in cognition.

Frequent Sexual Activity Predicts Specific Cognitive Abilities in Older Adults

Objectives

This study replicates and extends the findings of previous research (Wright, H., & Jenks, R. A. (2016). Sex on the brain! Associations between sexual activity and cognitive function in older age. Age and Ageing, 45, 313–317. doi:10.1093/ageing/afv197) which found a significant association between sexual activity (SA) and cognitive function in older adults. Specifically, this study aimed to generalize these findings to a range of cognitive domains, and to assess whether increasing SA frequency is associated with increasing scores on a variety of cognitive tasks.

Methods

Seventy-three participants aged 50–83 years took part in the study (38.4% male, 61.6% female). Participants completed the Addenbrooke’s Cognitive Examination-III (ACE-III) cognitive assessment and a questionnaire on SA frequency (never, monthly, or weekly), and general health and lifestyle.

Results

Weekly SA was a significant predictor of total ACE-III, fluency, and visuospatial scores in regression models, including age, gender, education, and cardiovascular health.

Discussion

Greater frequency of SA was associated with better overall ACE-III scores and scores on subtests of verbal fluency and visuospatial ability. Both of these tasks involve working memory and executive function, and links between sexual behavior, memory, and dopamine are discussed. The findings have implications for the maintenance of intimate relationships in later life.

Mixed Emotions: An Incentive Motivational Model of Sexual Deviance

Sexual offending behavior is a complex and multifaceted phenomenon. Most existing etiological models describe sexual offending behavior as a variant of offending behavior and mostly include factors referring to disinhibition and sexual deviance. In this article, we argue that there is additional value in describing sexual offending behavior as sexual behavior in terms of an incentive model of sexual motivation. The model describes sexual arousal as an emotion, triggered by a competent stimulus signaling potential reward, and comparable to other emotions coupled with strong bodily reactions. Consequently, we describe sexual offending behavior in terms of this new model with emphasis on the development of deviant sexual interests and preferences. Summarized, the model states that because sexual arousal itself is an emotion, there is a bidirectional relationship between sexual self-regulation and emotional self-regulation. Not only can sex be used to regulate emotional states (i.e., sexual coping), emotions can also be used, consciously or automatically, to regulate sexual arousal (i.e., sexual deviance). Preliminary support for the model is drawn from studies in the field of sex offender research as well as sexology and motivation research.

Impact of body iron store on sexual function: a comprehensive review and pilot cohort study in midlife women

PURPOSE

Both iron deficiency (ID) and female sexual dysfunction (FSD) affect more than 25% of the world population. The aim of this study was to identify a connection between these two conditions based on the existing literature and to investigate this interrelation in a small pilot cross-sectional study.

METHODS

A database search for publications referring to ID and FSD was conducted. The resulting common denominators were used to formulate hypotheses regarding the interaction of these diseases. Simultaneously, 45 healthy middle-aged women completed questionnaires about their sexual function and provided a blood sample for the purpose of determining ferritin and haemoglobin levels. The main outcome measures included an analysis of responses to questions on sexuality and partnership and of blood ferritin and haemoglobin levels. The secondary outcomes included an assessment of further influences on libido, such as sex hormones, menopausal status, health, and life satisfaction.

RESULTS

Altered monoaminergic cerebral metabolism, hyperprolactinaemia and hypothyroidism, impaired socioemotional interaction, increased anxiety, and depression in both, ID and FSD, account for the most comprehensive explanations for the postulated association between the two conditions. Despite a feasible assumption, our empirical findings failed to demonstrate any correlation between ID and FSD. We identified a certain impact of menopausal hormonal status on sexual function.

CONCLUSION

ID has no influence on FSD in the given population, although the literature suggests that FSD may at least be partly due to ID. Further research seems justified given the potential advantages for sexual health, considering that ID is an easily treatable disease.

Gender difference and correlation between sexuality, thyroid hormones, cognitive, and physical functions in elderly fit

PURPOSE

Sexuality in the elderly is related to psycho-physical well-being. Aim of this study was to analyze the correlation between sexual health, thyroid hormones, cognitive functions, and physical fitness in elderly population.

METHODS

Fifty-one fit adults were recruited (age: 71.9 ± 5.3 years, 26 females and 25 males). Sexuality was evaluated using the Changes in Sexual Functioning Questionnaire-short form (CSFQ-14) and the Sexual Attitude Scale (SAS). Thyroid function was assessed by measuring serum TSH, FT3, and FT4. Cognitive functions and depressive symptoms were evaluated by the Mini Mental State Examination (MMSE) test and Geriatric Depression Scale (GDS) scores. Subjects' physical fitness was evaluated using the following tests: Short Physical Performance Battery (SPPB), Handgrip test (HG), Timed Up and Go test (TUG), and 2-Minute step test (ST).

RESULTS

CSFQ-14 positively correlated with MMSE (p < 0.05) and negatively with GDS (p < 0.05), while thyroid function was not correlated with sexuality, in both genders. A negative relationship between FT4 vs. weight, FT3 vs. HG and FT3/FT4 ratio vs. ST were found (p = 0.05) in females, while in males, it occurred for TSH vs. TUG (p < 0.05); a positive relationship existed in females between FT4 vs. ST (p < 0.05). Finally, CSFQ-14 was significantly correlated with SPPB (p < 0.05), CST, TUG, and ST (p < 0.01), in both genders.

CONCLUSION

We demonstrated a strict relationship between active sexuality, preserved cognitive function and appropriate physical fitness in elderly subjects, independently from gender. Our preliminary data suggest that in elderly fit population, peripheral thyroxin deiodination may be a useful predictor of better physical performance and more successful aging.