Dopamine and sexual behavior

Role of tangeritin against cognitive impairments in transgenic Drosophila model of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. As there is no permanent cure for the disease, the use of herbal compounds with antioxidant potential will be an effective approach for controlling the progression of disease. In this context the effect of tangeritin (a polymethoxy flavone concentrated in the peels of citrus fruits) was studied at final doses of 5, 10 and 20 μM on PD model flies. The doses were established in diet and the PD flies were allowed to feed on it for 24 days. The effect was studied on cognitive impairments. Immunostaining of brain sections for tyrosine hydroxylase was also performed. The docking studies were also carried out to give a plausible binding site of tangeritin on alpha synuclein molecule. The results of the study showed that tangeritin is effective in improving the cognitive impairments.

Nucleus accumbens dopamine increases sexual motivation in sexually satiated male rats

RATIONALE

The influence of the main dopaminergic brain regions controlling copulation, the medial preoptic area (mPOA) and the nucleus accumbens (NAcc), on male rat sexual behavior expression has not been fully established.

OBJECTIVE

This work analyzes the sexual effects of dopamine (DA) receptor activation in the mPOA or the NAcc of sexually active male rats, with an intact (sexually experienced) or a reduced (sexually exhausted) sexual motivation.

METHODS

The non-specific DA receptor agonist apomorphine and the D2-like receptor agonist quinpirole were infused into the mPOA or the NAcc of sexually experienced or sexually exhausted male rats and their sexual behavior recorded.

RESULTS

DA receptor activation neither in the mPOA nor in the NAcc modified the copulatory behavior of sexually experienced male rats. DA receptor stimulation in the NAcc, but not in the mPOA, reversed the characteristic sexual inhibition of sexually satiated rats, and D2-like receptors were found to participate in this effect.

CONCLUSION

The optimal sexual performance of sexually experienced male rats cannot be further improved by DA receptor activation at either brain region. In sexually satiated rats, which are sexually inhibited and have a diminished sexual motivation, NAcc DA receptor stimulation appears to play a key role in their capacity to respond to a motivational significant stimulus, the receptive female, with the participation of D2-like receptors. Activation of DA receptors with the same drug, at the same dose and in the same brain region, produces different effects on copulatory behavior that depend on the animal's sexual motivational state.

The Role of Metabotropic Glutamate Receptors in Social Behavior in Rodents

The appropriate display of social behavior is critical for the well-being and survival of an individual. In many psychiatric disorders, including social anxiety disorder, autism spectrum disorders, depression and schizophrenia social behavior is severely impaired. Selective targeting of metabotropic glutamate receptors (mGluRs) has emerged as a novel treatment strategy for these disorders. In this review, we describe some of the behavioral paradigms used to assess different types of social behavior, such as social interaction, social memory, aggressive behavior and sexual behavior. We then focus on the effects of pharmacological modulation of mGluR1-8 on these types of social behavior. Indeed, accumulating evidence indicates beneficial effects of selective ligands of specific mGluRs in ameliorating innate or pharmacologically-induced deficits in social interaction and social memory as well as in reducing aggression in rodents. We emphasize the importance of future studies investigating the role of selective mGluR ligands on different types of social behavior to provide a better understanding of the neural mechanisms involved which, in turn, might promote the development of selective mGluR-targeted tools for the improved treatment of psychiatric disorders associated with social deficits.

DARPP-32 in the orchestration of responses to positive natural stimuli

Dopamine- and cAMP-regulated phosphoprotein (M_r 32 kDa, DARPP-32) is an integrator of multiple neuronal signals and plays a crucial role particularly in mediating the dopaminergic component of the systems involved in the evaluation of stimuli and the ensuing elaboration of complex behavioral responses (e.g., responses to reinforcers and stressors). Dopamine neurons can fire tonically or phasically in distinct timescales and in specific brain regions to code different behaviorally relevant information. Dopamine signaling is mediated mainly through the regulation of adenylyl cyclase activity, stimulated by D1-like or inhibited by D2-like receptors, respectively, that modulates cAMP-dependent protein kinase (PKA) function. The activity of DARPP-32 is finely regulated by its phosphorylation at multiple sites. Phosphorylation at the threonine (Thr) 34 residue by PKA converts DARPP-32 into an inhibitor of protein phosphatase 1, while the phosphorylation at the Thr75 residue turns it into an inhibitor of PKA. Thus, DARPP-32 is critically implicated in regulating striatal output in response to the convergent pathways that influence signaling of the cAMP/PKA pathway. This review summarizes some of the landmark and recent studies of DARPP-32-mediated signaling in the attempt to clarify the role played by DARPP-32 in the response to rewarding natural stimuli. Particularly, the review deals with data derived from rodents studies and discusses the involvement of the cAMP/PKA/DARPP-32 pathway in: 1) appetitive food-sustained motivated behaviors, 2) motivated behaviors sustained by social reward, 3) sexual behavior, and 4) responses to environmental enrichment.

Temporal associations between sexual function and cognitive function in community-dwelling older men: the Concord Health and Ageing in Men Project

Background

previous cross-sectional studies have reported bidirectional associations between sexual activity and cognitive function among older people. However, the temporal associations have not been studied.

Methods

community-dwelling men aged 70+ from the Concord Health and Ageing in Men Project were assessed. This study was based on 986 men at baseline, 829 men at 2 year and 595 men at 5-year follow-up. Sexual function using a standardised questionnaire (erectile function, sexual activity, sexual satisfaction, sexual desire) was analysed by generalised estimating equations to examine associations between changes in sexual function and changes in mini-mental state examination (MMSE) across three time points over 5 years. Age, BMI, comorbidity, self-rated health, smoking, number of medications, country of birth, education, marital status, depression and reproductive hormones were also measured at all time points.

Results

in unadjusted models, declines in erectile function (β = -0.317) and sexual activity (β = -0.575) over time were statistically significantly associated with a decline in MMSE over time. The associations observed in the unadjusted models remained after adjusting for a range of covariables. Declines in sexual satisfaction and sexual desire over time were not associated with changes in MMSE.

Conclusions

our findings provide evidence of a longitudinal temporal relationship between sexual activity and cognitive function. Further studies are warranted to examine whether maintaining a healthy sexual life has a positive effect on cognitive function in older men.

Neural circuits regulating sexual behaviors via the olfactory system in mice

Reproduction is essential for any animal species. Reproductive behaviors, or sexual behaviors, are largely shaped by external sensory cues exchanged during sexual interaction. In many animals, including rodents, olfactory cues play a critical role in regulating sexual behavior. What exactly these olfactory cues are and how they impact animal behavior have been a central question in the field. Over the past few decades, many studies have dedicated to identifying an active compound that elicits sexual behavior from crude olfactory components. The identified substance has served as a tool to dissect the sensory processing mechanisms in the olfactory systems. In addition, recent advances in genetic engineering, and optics and microscopic techniques have greatly expanded our knowledge of the neural mechanisms underlying the control of sexual behavior in mice. This review summarizes our current knowledge about how sexual behaviors are controlled by olfactory cues.

Rats selectively bred for showing divergent behavioral traits in response to stress or novelty or spontaneous yawning with a divergent frequency show similar changes in sexual behavior: the role of dopamine

Sexual behavior plays a fundamental role for reproduction in mammals and other animal species. It is characterized by an anticipatory and a consummatory phase, and several copulatory parameters have been identified in each phase, mainly in rats. Sexual behavior varies significantly across rats even when they are of the same strain and reared under identical conditions. This review shows that rats of the same strain selectively bred for showing a divergent behavioral trait when exposed to stress or novelty (i.e. Roman high and low avoidance rats, bred for their different avoidance response to the shuttle box, and high and low novelty exploration responders rats, bred for their different exploratory response to a novel environment) or a spontaneous behavior with divergent frequency (i.e. low and high yawning frequency rats, bred for their divergent yawning frequency) show similar differences in sexual behavior, mainly in copulatory pattern, but also in sexual motivation. As shown by behavioral pharmacology and intracerebral microdialysis experiments carried out mainly in Roman rats, these sexual differences may be due to a more robust dopaminergic tone present in the mesocorticolimbic dopaminergic system of one of the two sub-lines (e.g. high avoidance, high novelty exploration, and low yawning rat sub-lines). Thus, differences in genotype and/or in prenatal/postnatal environment lead not only to individual differences in temperament and environmental/emotional reactivity but also in sexual behavior. Because of the highly conserved mechanisms controlling reproduction in mammals, this may occur not only in rats but also in humans.

Mood, Meth, Condom Use, and Gender: Latent Growth Curve Modeling Results from a Randomized Trial

Methamphetamine use poses increased risk for HIV and other sexually transmitted infections. There is robust evidence that methamphetamine use increases sexual risk behavior, like condomless sex, primarily among men who have sex with men but also among heterosexual women and men. Gender differences have been found among women and men who use meth, and there is a high degree of interconnectedness between meth use, depression, and condomless sex. The aims of the current study are to evaluate the efficacy of a theory-based, tri-focal intervention designed to reduce depression, meth use, and condomless sex among women and men, and to examine gender as a moderator of efficacy. A total of 432 HIV-negative women and men who use meth participated in a two-arm randomized controlled trial and completed baseline and follow-up assessments at 4, 8, and 12 months. We used latent growth curve modeling techniques to analyze the data. Results showed that while all participants exhibited reductions in depression, meth use, and condomless sex, the intervention and comparison groups did not differ in changes over time. However, we did find a significant gender moderation effect, such that among men, those in the intervention arm reported greater reductions in meth use relative to those in the comparison group; reduced meth use was associated with reduced condomless sex, but not depression. In contrast, women in the intervention condition did not differ from women in the comparison condition in changes in any of the three outcome variables. Interventions targeting heterosexual women and men who use meth must be gender-specific, and take into account the unique vulnerabilities and experiences of women, including the perceived positive aspects of using meth, gendered power dynamics, higher depression, and violence.

Contemporary management of ejaculatory dysfunction

Although erectile dysfunction is the most common disorder of male sexual health, ejaculatory dysfunction is the most common form of sexual dysfunction experienced by men. Ejaculatory dysfunction covers a broad range of disorders that we have divided into four main categories: premature ejaculation, delayed ejaculation (DE)/anorgasmia, unsatisfactory sensation of ejaculation (including painful ejaculation and ejaculatory anhedonia), and absent ejaculate (including retrograde ejaculation and aspermia). We also cover several special scenarios including hematospermia, spinal cord injury and fertility with anejaculation. In this paper, we will review the anatomy and pathophysiology of normal ejaculation to establish the baseline knowledge of how this pathway can go awry. We will then briefly review the critical diagnostic criteria, pertinent steps in evaluation, risk factors, and causes (if known) for each of the ejaculatory disorders. Finally, the bulk of the paper will discuss current management strategies of each disorder.

Ethnopharmacology of Love

Background: Elixirs conferring eternal youth or inducing amatory and erotic attraction have been searched for without success. Lovesickness is a widespread affliction resulting from unrequited love and/or the impossibility for physical and emotional union. The symptoms are reflections of altered dopamine, serotonin, noradrenaline, testosterone and cortisol levels and range from frenzy and intrusive thinking to despair and depression, sharing traits with the neurochemistry of addiction and compulsive behavior disorder. Although it can seriously impact the quality of life, lovesickness is currently not considered in official disease classification systems. Consequently, no official therapeutic guidelines exist, leaving subjects to seek the cure on their own. Methods: We review literature of the past 2000 years dealing with the concept, diagnosis and the healing of lovesickness and contextualize it with neurochemical, ethnomedical, and ethnographic data. Since neurobiological and pharmacological connections between the love drive and the sex drive exist, we review also the literature about herbal an- and aphrodisiacs, focusing on their excitatory or calmative potential. Results: An overall consensus regarding socio-behavioral regimes exists for dealing with lovesickness from historical through contemporary literature. The herbal drugs used for treating lovesickness or inducing love passion do not possess the alleged properties. The pharmacological effects of aphrodisiacs are heterogeneous, including dopaminergic and adrenergic activities, but there is no evidence for any serotonergic effects. The libido-regulating properties of anaphrodisiacs seem to be associated with sedative and toxic effects or decreasing testosterone levels. CB2 receptors expressed on dopaminergic neurons of the ventral tegmental area, part of the brain's reward circuit, implicated with addiction, orgasm and strong emotions such as love, might constitute a new therapeutic target. Conclusion: The common food additive and CB2 agonist β-caryophyllene might have the potential to attenuate dopaminergic firing, quenching the reward and thus motivation associated with romantic love. From Greek mythology to modern history, cultural expressions and implications of love, sex and procreation is and was organized along hierarchical lines that put men on top. The neuronal predispositions and activities associated with falling in love will probably forever remain nature's and Eros' secret.

Sexual Dysfunctions in Female with Neurological Disorders

Female sexuality is a controversial issue due to its embarrassment and to paucity of literature publications. The neuroanatomy and neuromediators involved in female sexuality are important but not so fundamental as in men. There are three sexual female dysfunctions (SFD): primary, secondary, tertiary. In the primary one, the sexual dysfunction (SD) is correlated to the neurological disease, in the secondary the SD derives from the symptoms of the neurological disease, in the tertiary the SD is the psychological reaction to the effects of the disease. We analyse the FSD in neurological diseases, as the outcome of medulla trauma, multiple sclerosis, epilepsy, Alzheimer, Parkinson, diabetes, outcome of pelvic surgery. Female sexuality (FS) is difficult and complex compared to male sexuality. Women with medulla lesion feel some discomfort when having to go and speak to their doctor: they are afraid of pregnancy, sexual intercourses, bladder and rectal functions. In women with newly diagnosed multiple sclerosis, there is a tertiary sexual dysfunction. Medical therapy worsens female sexuality as in case of epilepsy. Emotional and behavioural disorders involve sexual dysfunctions in women with Alzheimer. In Parkinson, reduction of sexual desire involves break of sexual intercourses. SD are more frequent in complicated diabetes. In pelvic surgery, pelvic autonomic dysfunction and depression correlated to the oncology disease, contribute to the FSD. Sexual counselling, especially in young women with medulla lesion or multiple sclerosis, is the best therapy, and learning erotic extragenital areas able to make sensations similar to the orgasms.

Female Reproductive Behavior

Reproductive behavior is the behavior related to the production of offspring and includes all aspects from the establishment of mating systems, courtship, sexual behavior, and parturition to the care of young. In this chapter, I outline the hormonal regulation of the estrous cycle, followed by a description of the neural regulation of female sexual behavior. Ovarian hormones play an important role in the induction of ovulation and behavioral estrus, in which they interact closely with several neurotransmitters and neuropeptides to induce sexual behavior. This chapter discusses the latest research on the role of estrogen, progesterone, serotonin, dopamine, noradrenaline, oxytocin, and GABA in female mating behavior. In addition, the most relevant brain areas, such as the preoptic area and the ventromedial nucleus of the hypothalamus, in which these regulations take place, are discussed.

Childhood Abuse Experiences and the COMT and MTHFR Genetic Variants Associated With Male Sexual Orientation in the Han Chinese Populations: A Case-Control Study

BACKGROUND

Although it is widely acknowledged that genetic and environmental factors are involved in the development of male homosexuality, the causes are not fully understood.

AIM

To explore the association and interaction of childhood abuse experiences and genetic variants of the catechol-O-methyltransferase (COMT) and methylenetetrahydrofolate reductase (MTHFR) genes with the development of male homosexuality.

METHODS

A case-control study of 537 exclusively homosexual men and 583 exclusively heterosexual men was conducted, with data collected from March 2013 to August 2015. Data were analyzed using χ² tests and logistic regression models.

OUTCOMES

Sociodemographic characteristics, childhood abuse experiences, and polymorphisms of COMT at rs4680, rs4818, and rs6267 and MTHFR at rs1801133.

RESULTS

More frequent occurrence of physical (adjusted odds ratio [aOR] = 1.78), emotional (aOR = 2.07), and sexual (aOR = 2.53) abuse during childhood was significantly associated with the development of male homosexuality. The polymorphisms of MTHFR at rs1801133 and COMT at rs4818 also were significantly associated with the development of male homosexuality in the homozygote comparisons (T/T vs C/C at rs1801133, aOR = 1.68; G/G vs C/C at rs4818, aOR = 1.75). In addition, significant interaction effects between childhood abuse experiences and the COMT and MTHFR genetic variants on the development of male homosexuality were found.

CLINICAL TRANSLATION

This is the first time that an association of childhood abuse, COMT and MTHFR genetic variants, and their interactions with development of male homosexuality was exhaustively explored, which could help provide new insight into the etiology of male homosexuality.

STRENGTHS AND LIMITATIONS

Because homosexual men are a relatively obscure population, it was impossible to select the study participants by random sampling, which could lead to selection bias. In addition, because this was a case-control study, recall bias was inevitable, and we could not verify causality.

CONCLUSIONS

Childhood abuse and the COMT and MTHFR genetic variants could be positively associated with the development of homosexuality. However, it remains unknown how these factors jointly play a role in the development of homosexuality, and more studies in different ethnic populations and with a larger sample and a prospective design are required to confirm our findings. Qin J-B, Zhao G-L, Wang F, et al. Childhood Abuse Experiences and the COMT and MTHFR Genetic Variants Associated With Male Sexual Orientation in the Han Chinese Populations: A Case-Control Study. J Sex Med 2018;15:29-42.

Behavioral Modulation by Spontaneous Activity of Dopamine Neurons

Dopamine modulates a variety of animal behaviors that range from sleep and learning to courtship and aggression. Besides its well-known phasic firing to natural reward, a substantial number of dopamine neurons (DANs) are known to exhibit ongoing intrinsic activity in the absence of an external stimulus. While accumulating evidence points at functional implications for these intrinsic "spontaneous activities" of DANs in cognitive processes, a causal link to behavior and its underlying mechanisms has yet to be elucidated. Recent physiological studies in the model organism Drosophila melanogaster have uncovered that DANs in the fly brain are also spontaneously active, and that this activity reflects the behavioral/internal states of the animal. Strikingly, genetic manipulation of basal DAN activity resulted in behavioral alterations in the fly, providing critical evidence that links spontaneous DAN activity to behavioral states. Furthermore, circuit-level analyses have started to reveal cellular and molecular mechanisms that mediate or regulate spontaneous DAN activity. Through reviewing recent findings in different animals with the major focus on flies, we will discuss potential roles of this physiological phenomenon in directing animal behaviors.

Oxytocin induces penile erection and yawning when injected into the bed nucleus of the stria terminalis: Involvement of glutamic acid, dopamine, and nitric oxide

Oxytocin (5-100ng), but not Arg⁸-vasopressin (100ng), injected unilaterally into the bed nucleus of the stria terminalis (BNST) induces penile erection and yawning in a dose-dependent manner in male rats. The minimal effective dose was 20ng for penile erection and 5ng for yawning. Oxytocin responses were abolished not only by the oxytocin receptor antagonist d(CH₂)₅Tyr(Me)²-Orn⁸-vasotocin (1μg), but also by (+) MK-801 (1μg), an excitatory amino acid receptor antagonist of the N-methyl-d-aspartic acid (NMDA) subtype, SCH 23390 (1μg), a D1 receptor antagonist, but not haloperidol (1μg), a D2 receptor antagonist, and SMTC (40μg), an inhibitor of neuronal nitric oxide synthase, injected into the BNST 15min before oxytocin. Oxytocin-induced penile erection, but not yawning, was also abolished by CNQX (1μg), an excitatory amino acid receptor antagonist of the AMPA subtype. In contrast, oxytocin responses were not reduced by bicuculline (20ng), a GABA_A receptor antagonist, phaclofen (5μg), a GABA_B receptor antagonist, CP 376395, a CRF receptor-1 antagonist (5μg), or astressin 2B, a CRF receptor-2 antagonist (150ng). Considering the ability of NMDA (100ng) to induce penile erection and yawning when injected into the BNST and the available evidence showing possible interaction among oxytocin, glutamic acid, and dopamine in the BNST, oxytocin possibly activates glutamatergic neurotransmission in the BNST. This in turn leads to the activation of neural pathways projecting back to the paraventricular nucleus, medial preoptic area, ventral tegmental area, and/or ventral subiculum/amygdala, thereby inducing penile erection and yawning.

ICV galanin-like peptide stimulates non-contact erections but not touch-based erections in adult, sexually experienced male rats

Galanin-like peptide (GALP) is a neuropeptide transcribed only within the arcuate nucleus of the hypothalamus and is thought to be a mediator between energetics and reproductive function. Intracerebroventricular (ICV) injection of GALP is known to have effects on feeding, and to significantly increase gonadotropin releasing hormone- (GnRH-) mediated luteinizing hormone (LH) secretion. Furthermore, ICV GALP is known to stimulate fos production in the medial pre-optic area (mPOA) and to a lesser extent, the paraventricular nucleus (PVN). ICV injection of 5.0nmol GALP profoundly stimulates male rat sexual behavior. It is not known if GALP's effects on sex behavior are due to an increase in appetitive or mechanical (erectile) aspects of male sexual behavior. To determine this, sexually experienced male rats were cannulated in the lateral ventricle and injected with 5.0nmol GALP or vehicle. Immediately after injections, male rats were placed in an arena connected to a second arena via a tube with a fan. The second arena contained a steroid-primed female and her bedding. The male rat had olfactory but not visual or tactile contact with the female. We analyzed the amount of time the male rats spent investigating the air intake and the number of non-contact erections (NCEs) in a 30minute test. ICV GALP significantly (p<0.05) increased both the amount of time of olfactory investigations and NCEs compared to vehicle. In a second set of animals, we tested if ICV GALP could stimulate touch-based erections. GALP had no significant effect on touch-based erections compared to vehicle. These data suggest that GALP's activation of fos within the mPOA is indicative of its action to stimulate the appetitive aspects of male sexual behavior.

The right way to kiss: directionality bias in head-turning during kissing

Humans have a bias for turning to the right in a number of settings. Here we document a bias in head-turning to the right in adult humans, as tested in the act of kissing. We investigated head-turning bias in both kiss initiators and kiss recipients for lip kissing, and took into consideration differences due to sex and handedness, in 48 Bangladeshi heterosexual married couples. We report a significant male bias in the initiation of kissing and a significant bias in head-turning to the right in both kiss initiators and kiss recipients, with a tendency among kiss recipients to match their partners’ head-turning direction. These interesting outcomes are explained by the influences of societal learning or cultural norms and the potential neurophysiological underpinnings which together offer novel insights about the mechanisms underlying behavioral laterality in humans.

The Impact of Oxytocin Gene Knockout on Sexual Behavior and Gene Expression Related to Neuroendocrine Systems in the Brain of Female Mice

Social relations are built and maintained from the interaction among individuals. The oxytocin (OT), vasopressin (VP), estrogen, dopamine, and their receptors are involved in the modulation of sexual behavior in females. This study aimed to analyze the impact of OT gene knockout (OTKO) on sexual behavior and the gene expression of oxytocin (OTR), estrogen alpha (ERα), estrogen beta (ERβ), vasopressin (V1aR), and dopamine (D2R) receptors in the olfactory bulb (OB), prefrontal cortex (PFC), hippocampus (HPC), and hypothalamus (HPT), as well as in the synthesis of VP in the HPT of female mice. Wild-type (WT) littermates were used for comparisons. The CDNAs were synthesized by polymerase chain reaction and the gene expression was calculated with the 2-ΔΔCt formula. Our results showed that the absence of OT caused an increase in the frequency and duration of non-receptive postures and a decrease in receptive postures in the OTKO. OTKO females showed a significant decrease in the gene expression of OTR in the HPC, V1aR in the HPT, and ERα and ERβ in the PFC. There was no significant difference in the gene expression of D2R of OTKO. However, OTKO showed an increased gene expression of V1aR in the HPC. There is no significant difference in VP mRNA synthesis in the HPT between OTKO and WT. Our findings demonstrate that the absence of OT leads to significant changes in the expression of the studied genes (OTR, ERα, ERβ, V1aR), and these changes may contribute to the decreased sexual behavior observed in OTKO females.

KNDy neurone activation prior to the LH surge of the ewe is disrupted by LPS

In the ewe, steroid hormones act on the hypothalamic arcuate nucleus (ARC) to initiate the GnRH/LH surge. Within the ARC, steroid signal transduction may be mediated by estrogen receptive dopamine-, β-endorphin- or neuropeptide Y (NPY)-expressing cells, as well as those co-localising kisspeptin, neurokinin B (NKB) and dynorphin (termed KNDy). We investigated the time during the follicular phase when these cells become activated (i.e., co-localise c-Fos) relative to the timing of the LH surge onset and may therefore be involved in the surge generating mechanism. Furthermore, we aimed to elucidate whether these activation patterns are altered after lipopolysaccharide (LPS) administration, which is known to inhibit the LH surge. Follicular phases of ewes were synchronised by progesterone withdrawal and blood samples were collected every 2 h. Hypothalamic tissue was retrieved at various times during the follicular phase with or without the administration of LPS (100 ng/kg). The percentage of activated dopamine cells decreased before the onset of sexual behaviour, whereas activation of β-endorphin decreased and NPY activation tended to increase during the LH surge. These patterns were not disturbed by LPS administration. Maximal co-expression of c-Fos in dynorphin immunoreactive neurons was observed earlier during the follicular phase, compared to kisspeptin and NKB, which were maximally activated during the surge. This indicates a distinct role for ARC dynorphin in the LH surge generation mechanism. Acute LPS decreased the percentage of activated dynorphin and kisspeptin immunoreactive cells. Thus, in the ovary-intact ewe, KNDy neurones are activated prior to the LH surge onset and this pattern is inhibited by the administration of LPS.

Dopamine, Noradrenaline and Differences in Sexual Behavior between Roman High and Low Avoidance Male Rats: A Microdialysis Study in the Medial Prefrontal Cortex

Roman High- (RHA) and Low-Avoidance (RLA) outbred rats, which differ for a respectively rapid vs. poor acquisition of the active avoidance response in the shuttle-box, display differences in sexual activity when put in the presence of a sexually receptive female rat. Indeed RHA rats show higher levels of sexual motivation and copulatory performance than RLA rats, which persist also after repeated sexual activity. These differences have been correlated to a higher tone of the mesolimbic dopaminergic system of RHA rats vs. RLA rats, revealed by the higher increase of dopamine found in the dialysate obtained from the nucleus accumbens of RHA than RLA rats during sexual activity. This work shows that extracellular dopamine and noradrenaline (NA) also, increase in the dialysate from the medial prefrontal cortex (mPFC) of male RHA and RLA rats put in the presence of an inaccessible female rat and more markedly during direct sexual interaction. Such increases in dopamine (and its main metabolite 3,4-dihydroxyphenylacetic acid, DOPAC) and NA were found in both sexually naïve and experienced animals, but they were higher: (i) in RHA than in RLA rats; and (ii) in sexually experienced RHA and RLA rats than in their naïve counterparts. Finally, the differences in dopamine and NA in the mPFC occurred concomitantly to those in sexual activity, as RHA rats displayed higher levels of sexual motivation and copulatory performance than RLA rats in both the sexually naïve and experienced conditions. These results suggest that a higher dopaminergic tone also occurs in the mPFC, together with an increased noradrenergic tone, which may be involved in the different copulatory patterns found in RHA and RLA rats, as suggested for the mesolimbic dopaminergic system.

Sexual Disorders Caused by Antidepressants: Considerations in the Context of Brain Hemisphere Functions

All phases of normal sexual activity are under the control of the right hemisphere coupled with limbic structures, and depression is characterized by the functional insufficiency of this system. At the same time, those modern antidepressants that cause sexual disorders are activating the left hemisphere and determine its domination on the expense of the right one and disturb free and spontaneous emotional interrelationships, sexual behavior and pleasure. Those antidepressants that do not cause sexual dysfunction are not activating predominantly the left hemisphere structures and activate the limbic brain zones responsible for reward, reinforcement and emotional excitement.

The role of ghrelin signalling for sexual behaviour in male mice

Ghrelin, a gut-brain signal, is well known to regulate energy homeostasis, food intake and appetite foremost via hypothalamic ghrelin receptors (GHS-R1A). In addition, ghrelin activates the reward systems in the brain, namely the mesolimbic dopamine system, and regulates thereby the rewarding properties of addictive drugs as well as of palatable foods. Given that the mesolimbic dopamine system mandates the reinforcing properties of addictive drugs and natural rewards, such as sexual behaviour, we hypothesize that ghrelin plays an important role for male sexual behaviour, a subject for the present studies. Herein we show that ghrelin treatment increases, whereas pharmacological suppression (using the GHSR-1A antagonist JMV2959) or genetic deletion of the GHS-R1A in male mice decreases the sexual motivation for as well as sexual behaviour with female mice in oestrus. Pre-treatment with L-dopa (a dopamine precursor) prior to treatment with JMV2959 significantly increased the preference for female mouse compared with vehicle treatment. On the contrary, treatment with 5-hydroxythyptohan (a precursor for serotonin) prior to treatment with JMV2959 decreased the sexual motivation compared to vehicle. In separate experiments, we show that ghrelin and GHS-R1A antagonism do not affect the time spent over female bedding as measured in the androgen-dependent bedding test. Collectively, these data show that the hunger hormone ghrelin and its receptor are required for normal sexual behaviour in male mice and that the effects of the ghrelin signalling system on sexual behaviour involve dopamine neurotransmission.

Sex on the brain! Associations between sexual activity and cognitive function in older age

BACKGROUND

the relationship between cognition and sexual activity in healthy older adults is under-researched. A limited amount of research in this area has shown that sexual activity is associated with better cognition in older men. The current study explores the possible mediating factors in this association in men and women, and attempts to provide an explanation in terms of physiological influences on cognitive function.

METHODS

using newly available data from Wave 6 of the English Longitudinal Study of Ageing, the current study explored associations between sexual activity and cognition in adults aged 50-89 (n = 6,833). Two different tests of cognitive function were analysed: number sequencing, which broadly relates to executive function, and word recall, which broadly relates to memory.

RESULTS

after adjusting for age, education, wealth, physical activity, depression, cohabiting, self-rated health, loneliness and quality of life, there were significant associations between sexual activity and number sequencing and recall in men. However, in women there was a significant association between sexual activity and recall, but not number sequencing.

CONCLUSIONS

possible mediators of these associations (e.g. neurotransmitters) are discussed. The cross-sectional nature of the analysis is limiting, but provides a promising avenue for future explorations and longitudinal studies. The findings have implications for the promotion of sexual counselling in healthcare settings, where maintaining a healthy sex life in older age could be instrumental in improving cognitive function and well-being.

The maternal brain and its plasticity in humans

This article is part of a Special Issue "Parental Care". Early mother-infant relationships play important roles in infants' optimal development. New mothers undergo neurobiological changes that support developing mother-infant relationships regardless of great individual differences in those relationships. In this article, we review the neural plasticity in human mothers' brains based on functional magnetic resonance imaging (fMRI) studies. First, we review the neural circuits that are involved in establishing and maintaining mother-infant relationships. Second, we discuss early postpartum factors (e.g., birth and feeding methods, hormones, and parental sensitivity) that are associated with individual differences in maternal brain neuroplasticity. Third, we discuss abnormal changes in the maternal brain related to psychopathology (i.e., postpartum depression, posttraumatic stress disorder, substance abuse) and potential brain remodeling associated with interventions. Last, we highlight potentially important future research directions to better understand normative changes in the maternal brain and risks for abnormal changes that may disrupt early mother-infant relationships.

Differential organization of male copulatory patterns in high- and low-yawning-frequency sublines versus outbred Sprague-Dawley rats

The temporal organization of masculine sexual behavior in rats is highly stereotyped; involving a sequence of mounts, intromissions and ejaculations. Sexual behavior has been described in exogamic and genetically manipulated rodent species. In this work, we compare the male sexual behavior of outbred Sprague-Dawley (SD) to those of rats inbred for high (HY)- and low (LY)- spontaneous yawning frequency. In the first experiment, the percentage of inexperienced rats' ejaculatory behavior is significantly lower in the HY and LY respect to Sprague-Dawley rats. The latency to ejaculate for inexperienced HY was shorter than the LY and SD rats. In the second experiment, we examined the differences between inbred sublines and Sprague-Dawley rats once the subjects had become sexually experienced after four copulatory sessions. HY rats still have slower proportion of ejaculators respect to LY and SD rats. Additionally, postejaculatory latencies were longer for HY rats, with longer intercopulatory intervals and higher number of copulatory bouts that delayed ejaculation. Both sublines show lower copulatory efficiency respect to SD rats. In conclusion, both sublines show alterations in the temporal organization of sexual motor pattern that are due at least partially to strong inbreeding process to select them.

Copulation is reactivated by bromocriptine in male rats after reaching sexual satiety with a same sexual mate

Male sexual satiety has been associated with a decrease in dopamine levels. Spontaneous recovery of copulatory behavior begins at least 72 h after sexual satiety is reached or in the condition in which a sexually-satiated male is exposed to a new receptive female distinct from the one with which sexual satiety was reached. The aim of the present study was to explore whether dopaminergic activation by bromocriptine (BrCr) can reactivate copulatory behavior with the same sexual mate immediately after sexual satiety is reached. Male rats were divided into three groups exposed to one of the following three conditions: 1) administration of 2 mg/kgs.c. of BrCr and exposure to the same female with whom sexual satiety was previously reached; 2) administration of 0.3 mLs.c. of the vehicle solution with exposure to the same female with whom sexual satiety was reached; and, 3) exposure to a new receptive female after sexual satiety was reached. Results showed that BrCr significantly reactivated copulatory capability in sexually-satiated males with the same receptive female. In contrast, no males in the vehicle group ejaculated with the same female after reaching sexual exhaustion. Copulation was reactivated by BrCr in a way similar to that observed in untreated males exposed to a new receptive female (i.e., the Coolidge effect). The reversal of sexual satiety in the males treated with BrCr could be explained by its action on D2 family receptors, which promotes a reactivation of sexual motivation at a level sufficient to allow renewed copulation with the same female mate.

Lust, attraction, and attachment in mammalian reproduction

This paper proposes that mammals exhibit three primary emotion categories for mating and reproduction: (1) the sex drive, or lust, characterized by the craving for sexual gratification; (2) attraction, characterized by increased energy and focused attention on one or more potential mates, accompanied in humans by feelings of exhilaration, "intrusive thinking" about a mate, and the craving for emotional union with this mate or potential mate; and (3) attachment, characterized by the maintenance of close social contact in mammals, accompanied in humans by feelings of calm, comfort, and emotional union with a mate. Each emotion category is associated with a discrete constellation of neural correlates, and each evolved to direct a specific aspect of reproduction. The sex drive is associated primarily with the estrogens and androgens; it evolved to motivate individuals to seek sexual union. The attraction system is associated primarily with the catecholamines; it evolved to facilitate mate choice, enabling individuals to focus their mating effort on preferred partners. The attachment system is associated primarily with the peptides, vasopressin, and oxytocin; it evolved to motivate individuals to engage in positive social behaviors and assume species-specific parental duties.During the evolution of the genus Homo, these emotion systems became increasingly independent of one another, a phenomenon that contributes to human mating flexibility and the wide range of contemporary human mating and reproductive strategies.

PPL2ab neurons restore sexual responses in aged Drosophila males through dopamine

Male sexual desire typically declines with ageing. However, our understanding of the neurobiological basis for this phenomenon is limited by our knowledge of the brain circuitry and neuronal pathways controlling male sexual desire. A number of studies across species suggest that dopamine (DA) affects sexual desire. Here we use genetic tools and behavioural assays to identify a novel subset of DA neurons that regulate age-associated male courtship activity in Drosophila. We find that increasing DA levels in a subset of cells in the PPL2ab neuronal cluster is necessary and sufficient for increased sustained courtship in both young and aged male flies. Our results indicate that preventing the age-related decline in DA levels in PPL2ab neurons alleviates diminished courtship behaviours in male Drosophila. These results may provide the foundation for deciphering the circuitry involved in sexual motivation in the male Drosophila brain.

We currently lack a detailed understanding of the neurobiological basis for the decline of male sexual desire with age. Here the authors demonstrate that restoring impaired dopaminergic signalling in a specific cluster of neurons in the Drosophila brain increases sexual behaviour in ageing male flies.

The exposure to Trichilia catigua (catuaba) crude extract impairs fertility of adult female rats but does not cause reproductive damage to male offspring

ETHNOPHARMACOLOGICAL RELEVANCE

Trichilia catigua is broadly used in folk medicine due to its mental and physical tonic activities and stimulant effects. In animal models, its antidepressant-like effects have been associated with the dopaminergic (DA) system modulation, which has an important role on maternal behavior and male offspring reproductive development.

AIM OF THE STUDY

Since little is known about the adverse effects of the exposure to T. catigua crude extract (CAT) in rats, specially regarding maternal homeostasis and offspring development, the aim of the present study was to evaluate whether CAT exposure may influence maternal toxicity parameters and behavior or disrupt male offspring physical and reproductive development.

MATERIAL AND METHODS

Dams were treated daily (by gavage) with 400mg/kg of CAT or vehicle (control=CTR) throughout pregnancy and lactation. Fertility and maternal behavior tests were conducted in dams. Male offspring reproductive and behavioral parameters were analyzed.

RESULTS

Dams exposed to CAT showed increased pre- and post-implantation losses rates when compared to CTR group. No significant changes regarding maternal behavior or male offspring parameters were observed.

CONCLUSION

In conclusion, maternal exposure to CAT interfered with implantation during the initial phases of pregnancy but did not induce changes on maternal behavior or male offspring reproductive and behavioral parameters.

Dopamine receptors play distinct roles in sexual behavior expression of rats with a different sexual motivational tone

Dopamine (DA) plays a central role in the expression of male sexual behavior. The effects of DA-enhancing drugs on copulation seem to vary depending on the dose of the agonist used, the type of DA receptor activated, and the sexual condition of the animals. The aim of the present study was to carry out a systematic analysis of the effects of dopaminergic agonists on the expression of male sexual behavior by sexually competent rats in different sexual motivational states, that is when sexually active (sexually experienced) and when temporarily inhibited (sexually exhausted). To this end, the same doses of the nonselective DA receptor agonist apomorphine, the selective D2-like DA receptor agonist quinpirole, and the selective D1-like DA receptor agonist SKF38393 were injected intraperitoneally to sexually experienced or sexually exhausted male rats and their sexual behavior was recorded. Low apomorphine doses induced expression of sexual behavior in sexually satiated rats, but only reduced the intromission latency of sexually experienced rats. SKF38393 facilitated the expression of sexual behavior by sexually exhausted rats, but not that of sexually experienced males and quinpirole did not exert an effect in both types of animal. In line with these results, the apomorphine-induced reversal of sexual exhaustion was blocked by the D1-like receptor antagonist SCH23390. The data suggest that DA receptors play distinct roles in the expression of sexual behavior by male rats depending on their motivational state and that activation of D1-like receptors promotes the expression of sexual behavior in satiated rats.

Effects of methylphenidate and MDMA on appraisal of erotic stimuli and intimate relationships

Methylphenidate mainly enhances dopamine neurotransmission whereas 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") mainly enhances serotonin neurotransmission. However, both drugs also induce a weaker increase of cerebral noradrenaline exerting sympathomimetic properties. Dopaminergic psychostimulants are reported to increase sexual drive, while serotonergic drugs typically impair sexual arousal and functions. Additionally, serotonin has also been shown to modulate cognitive perception of romantic relationships. Whether methylphenidate or MDMA alter sexual arousal or cognitive appraisal of intimate relationships is not known. Thus, we evaluated effects of methylphenidate (40 mg) and MDMA (75 mg) on subjective sexual arousal by viewing erotic pictures and on perception of romantic relationships of unknown couples in a double-blind, randomized, placebo-controlled, crossover study in 30 healthy adults. Methylphenidate, but not MDMA, increased ratings of sexual arousal for explicit sexual stimuli. The participants also sought to increase the presentation time of implicit sexual stimuli by button press after methylphenidate treatment compared with placebo. Plasma levels of testosterone, estrogen, and progesterone were not associated with sexual arousal ratings. Neither MDMA nor methylphenidate altered appraisal of romantic relationships of others. The findings indicate that pharmacological stimulation of dopaminergic but not of serotonergic neurotransmission enhances sexual drive. Whether sexual perception is altered in subjects misusing methylphenidate e.g., for cognitive enhancement or as treatment for attention deficit hyperactivity disorder is of high interest and warrants further investigation.

Review: neuroestrogen regulation of socio-sexual behavior of males

It is thought that estrogen (neuroestrogen) synthesized by the action of aromatase in the brain from testosterone activates male socio-sexual behaviors, such as aggression and sexual behavior in birds. We recently found that gonadotropin-inhibitory hormone (GnIH), a hypothalamic neuropeptide, inhibits socio-sexual behaviors of male quail by directly activating aromatase and increasing neuroestrogen synthesis in the preoptic area (POA). The POA is thought to be the most critical site of aromatization and neuroestrogen action for the regulation of socio-sexual behavior of male birds. We concluded that GnIH inhibits socio-sexual behaviors of male quail by increasing neuroestrogen concentration beyond its optimal concentration in the brain for expression of socio-sexual behavior. On the other hand, it has been reported that dopamine and glutamate, which stimulate male socio-sexual behavior in birds and mammals, inhibit the activity of aromatase in the POA. Multiple studies also report that the activity of aromatase or neuroestrogen is negatively correlated with changes in male socio-sexual behavior in fish, birds, and mammals including humans. Here, we review previous studies that investigated the role of neuroestrogen in the regulation of male socio-sexual behavior and reconsider the hypothesis that neuroestrogen activates male socio-sexual behavior in vertebrates. It is considered that basal concentration of neuroestrogen is required for the maintenance of male socio-sexual behavior but higher concentration of neuroestrogen may inhibit male socio-sexual behavior.

Dopamine receptor gene d4 polymorphisms and early sexual onset: gender and environmental moderation in a sample of african-american youth

PURPOSE

Early sexual onset and its consequences disproportionately affect African-American youth, particularly male youth. The dopamine receptor D4 gene (DRD4) has been linked to sexual activity and other forms of appetitive behavior, particularly for male youth and in combination with environmental factors (gene × environment [G × E] effects). The differential susceptibility perspective suggests that DRD4 may exert this effect by amplifying the effects of both positive and negative environments. We hypothesized that DRD4 status would amplify the influence of both positive and negative neighborhood environments on early sexual onset among male, but not female, African-Americans.

METHODS

Hypotheses were tested with self-report, biospecimen, and census data from five prospective studies of male and female African-American youth in rural Georgia communities, N = 1,677. Early sexual onset was defined as intercourse before age 14.

RESULTS

No significant G × E findings emerged for female youth. Male youth with a DRD4 long allele were more likely than those with two DRD4 short alleles to report early sexual onset in negative community environments and not to report early onset in positive community environments.

CONCLUSIONS

Dopaminergic regulation of adolescent sexual behaviors may operate differently by gender. DRD4 operated as an environmental amplification rather than a vulnerability factor.

An enriched rearing environment calms adult male rat sexual activity: implication for distinct serotonergic and hormonal responses to females

Early life events induce alterations in neural function in adulthood. Although rearing in an enriched environment (EE) has a great impact on behavioral development, the effects of enriched rearing on sociosexual behavior remain unclear. In this study, we investigated the effects of rearing in an EE on male copulatory behavior and its underlying neurobiological mechanisms in Wistar-Imamichi rats. Three-week-old, recently weaned rats were continuously subjected to a standard environment (SE) or an EE comprised of a large cage with several objects, such as toys, tunnels, ladders, and a running wheel. After 6 weeks, rats reared in an EE (EE rats) showed decreased sexual activity compared with rats reared in a SE (SE rats). This included a lower number of ejaculations and longer latencies in three consecutive copulatory tests. In addition, EE rats showed decreased emotional responsiveness and less locomotor behavior in an open field. In a runway test, on the other hand, sexual motivation toward receptive females in EE males was comparable to that of SE males. Furthermore, following exposure to a female, increases in serotonin levels in the nucleus accumbens and the striatum were significantly suppressed in EE males, whereas dopaminergic responses were similar between the groups. Female-exposure-induced increases in the levels of plasma corticosterone and testosterone were also suppressed in EE rats compared to SE rats. These data suggest that rearing in an EE decreases male copulatory behavior, and serotonin and hormonal regulating systems may regulate the differences in sociosexual interactions that result from distinct rearing environments.

Factors associated with sexual arousal, sexual sensation seeking and sexual satisfaction among female African American adolescents

BACKGROUND

Sexuality-related constructs, such as sexual arousal, sexual sensation seeking (SSS) and sexual satisfaction, have been related to sexual behaviours that place one at risk of adverse consequences, such as sexually transmissible infections, HIV and unintended pregnancy. The biopsychosocial model posits an array of factors, ranging from social environmental factors to biological and psychological predispositions, that may be associated with these sexuality constructs in adolescents.

METHODS

Female African Americans aged 14-20 years were recruited from reproductive health clinics for an HIV intervention. Baseline survey and follow-up DNA data (n=304) were used to assess biological, psychological and social environmental associations with the sexuality constructs of arousal, SSS and sexual satisfaction.

RESULTS

Multivariate linear regression analysis revealed that a higher depressive symptom rating was associated with higher arousability, whereas short serotonin transporter gene allele(s) status was associated with lower arousability. Impulsivity and perceived peer norms supportive of unsafe sexual behaviours were associated with increased SSS, whereas short serotonin transporter gene allele(s) status was associated with lower SSS. Higher social support was associated with higher levels of sexual satisfaction, whereas short serotonin transporter gene allele(s) status was associated with lower satisfaction. The sexuality constructs were also significantly related to the number of sex partners, the frequency of vaginal sex and the number of unprotected vaginal sex acts in the past 6 months.

CONCLUSIONS

The findings emphasise the importance of understanding biopsychosocial factors, including the role of serotonin as an indicator of natural variations in sexual inclination and behaviours, that influence sexuality constructs, which, in turn, are associated with sexual behaviours, to allow further refinement of sexual health clinical services and programs and promote the development of healthy sexuality.

Effect of Hydroalcoholic Extract of Cydonia oblonga Miller (Quince) on Sexual Behaviour of Wistar Rats

Cydonia oblonga Miller (quince) is regarded as a potent libido invigorator in Tib-e-Nabvi and Unani System of Medicine. This study was carried out to evaluate the aphrodisiac activity of the hydroalcoholic extract of the fruits of Cydonia oblonga Miller (quince) in Wistar rats. The extract was administered orally by gavage in the dose of 500 mg/kg and 800 mg/kg body weight per day as a single dose for 28 days. The observed parameters were mounting frequency, assessment of mating performance, and orientation activities towards females, towards the environment, and towards self. The results showed that after administration of the extract mounting frequency and the mating performance of the rats increased highly significantly (P < 0.01). The extract also influenced the behaviour of treated animals in comparison to nontreated rats in a remarkable manner, making them more attracted to females. These effects were observed in sexually active male Wistar rats.