Anticipatory 50-kHz Precontact Ultrasonic Vocalizations and Sexual Motivation: Characteristic Pattern of Ultrasound Subtypes in an Individual Analyzed Profile

We verified the hypothesis of the existence of forms of individual-specific differences in the emission of anticipatory precontact vocalization (PVs) indicating individualization related to sexual experience and motivation in male rats. Long-Evans males were individually placed in a chamber and 50-kHz ultrasounds were recorded during 5-min periods. In experiment 1, PVs were recorded before the introduction of a female in four consecutive sessions during the acquisition of sexual experience. In experiment 2, PVs were analyzed in three groups of sexually experienced males: with the highest, moderate, and the lowest sexual motivation based on previous copulatory activity. In both experiments, the total number of ultrasounds, as well as 14 different specific subtypes, was measured. The ultrasound profiles for each male were created by analyzing the proportions of specific dominant subtypes of so-called 50-kHz calls. We decided that the dominant ultrasounds were those that represented more than 10% of the total recorded signals in a particular session. The number of PVs was positively correlated with the acquisition of sexual experience and previous copulatory efficiency (measured as the number of sessions with ejaculation). Furthermore, PVs showed domination of the frequency modulated signals (complex and composite) as well as flat and short with upward ramp ultrasounds with some individual differences, regardless of the level of sexual motivation. The results show a characteristic pattern of PVs and confirm the hypothesis that the number of PVs is a parameter reflecting the level of sexual motivation.

Male infertility, metabolic syndrome and obesity

The review article is devoted to the current understanding of the mechanisms that can have a negative impact on the reproductive function of men with metabolic syndrome and obesity. The article presents the results of clinical studies proving the existence of a relationship between the severity of metabolic disorders, copulatory activity, ejaculate parameters, the likelihood of pregnancy, as well as the health of the offspring.

Aphrodisiac property of aqueous and methanolic extracts of Raphia vinifera (Arecaceae) in sexually experienced male rats

Background: Raphia vinifera (Arecaceae) is a medicinal plant commonly used as a sexual enhancer. Objective: To investigate the aphrodisiac potential of aqueous extract (AE) and methanolic extract (ME) of R. vinifera in sexually experienced male rats. Materials and Methods: Thirty male Wistar rats were randomly distributed into six groups (5 rats per group) and administered for 14 days with distilled water (10 ml/kg), sildenafil citrate (1.44 mg/kg), and AE or ME of R. vinifera (100 or 500 mg/kg). The copulatory activity was tested on days 0, 7, and 14 using receptive females. Further, on day 14, rats were sacrificed and biochemical analyses (testosterone, total protein, and acid phosphatase) were performed. Results: Sildenafil citrate significantly decreased the intromission latency (day 14, p = 0.04) and frequency (days 7 and 14, p = 0.03) but increased the mount frequency (day 14, p = 0.04), compared with control. Remarkably, R. vinifera enhanced the sexual activity by significantly decreasing the intromission latency (AE and ME, 500 mg/kg, day 14, p = 0.04) and increasing the mount frequency (AE and ME, 100 mg/kg, day 7, p = 0.02) compared with control. Moreover, R. vinifera improved plasmatic (AE, 100 mg/kg, p = 0.03; AE, 500 mg/kg, p = 0.001; ME, 100 mg/kg, p = 0.01) and testicular (AE, 100 mg/kg, p = 0.001; AE, 500 mg/kg, p = 0.01; ME, 100 mg/kg, p = 0.001; ME, 500 mg/kg, p = 0.01) testosterone levels as well as plasmatic total proteins concentration (ME, 500 mg/kg, p = 0.04). Conclusion: These findings showed that R. vinifera possesses an aphrodisiac property which could further justify its folkloric use in traditional medicine as a sexual enhancer.

Neuroendocrine Mechanisms Involved in Male Sexual and Emotional Behavior

Objective:The aim of this narrative review was to analyze the role played by brain areas, neurohormones and neurotransmitters in the regulation of emotional and sexual behavior in the male.Methods:We analyzed the currently available literature dealing with brain structures, neurotransmitters and neurohormones involved in the regulation of emotional and sexual behavior in the male.Results:A common brain pathway is involved in these two aspects. The Hippocampus seems to control the signals coming from the external environment, while the amygdala and the hypothalamus control the response to social stimuli. Stimulation of amygdala in the animal models increases sexual performance, while it triggers violent emotional responses. Stimulation of the hypothalamus causes reactions of violent anger and increases sexual activity. Catecholaminergic stimulation of the amygdala and hypothalamus increases emotional and sexual behavior, while serotonin plays an inhibitory role. Cholinergic inhibition leads to a suppression of copulatory activity, while the animal becomes hyperemotive. Opioids, such as β-endorphin and met-enkephalin, reduce copulatory activity and induce impotence. Gonadal steroid hormones, such as estrogen in female and testosterone in male, which play a major role in the control of sexual behavior and gender difference have been highlighted in this review. Vasopressin, oxytocin and their receptors are expressed in high density in the “social behavior neural network” and play a role as signal system controlling social behavior. Finally, the neuropeptide kisspeptin and its receptors, located in the limbic structures, mediate olfactory control of the gonadotropic axis.Conclusion:Further studies are needed to evaluate possible implications in the treatment of psychosexual and reproductive disorders.

All too human: responses to same-sex copulation in the common cockchafer (Melolontha melolontha (L.)), 1834–1900

Beginning in 1834, entomologists across Europe began reporting same-sex copulatory activity in a variety of insect species, sometimes between species or genera. Most communications concerned male-male couplings of the common cockchafer (Melolontha melolontha, syn. M. vulgaris). These reports offer a unique snapshot of how nineteenth-century naturalists responded when they were required to explain precisely what was natural in their observations. Initial communications of same-sex couplings were mainly accompanied by exclamations of surprise and the rhetoric of disapproval. Such activity was explained either by the assumption that one of the parties must in some way have a female anatomy or that blind or excessive lust compelled more virile individuals to force copulation upon weaker ones. As these explanations were questioned, more complex and controversial theories founded in fashionable evolutionary theories were forwarded as means of assimilating the phenomenon within hegemonic constructions of sexuality. These came from both within entomological circles and from outside observers whose primary interest was in theorizing human eroticism. This article follows a particularly intense dispute which erupted following the claim by one of France's leading naturalists, Henri Gadeau de Kerville, that the homoerotic activity demonstrated by male cockchafers evidenced the existence of a distinctly “homosexual” instinct. By 1900 no single taxonomy of non-human homoeroticism dominated intellectual discourse on the subject. Although zoological observations of same-sex eroticism continued to be made through the twentieth century, Melolontha were left in relative peace.

Prior selfing and the selfing syndrome in animals: an experimental approach in the freshwater snailBiomphalaria pfeifferi

SummaryInbreeding species of hermaphroditic animals practising copulation have been characterized by few copulations, no waiting time (the time that an isolated individual waits for a partner before initiating reproduction compared with paired individuals) and limited inbreeding (self-fertilization) depression. This syndrome, which has never been fully studied before in any species, is analysed here in the highly selfing freshwater snailBiomphalaria pfeifferi. We conducted an experiment under laboratory conditions over two generations (G1and G2) using snails sampled from two populations (100 individuals per population). G1individuals were either isolated or paired once a week (potentially allowing for crosses), and monitored during 29 weeks for growth, fecundity and survival. Very few copulations were observed in paired snails, and there was a positive correlation in copulatory activity (e.g. number of copulations) between the male and female sexual roles. The waiting time was either null or negative, meaning that isolated individuals initiated reproduction before paired ones. G2offspring did not differ in hatching rate and survival (to 28 days) between treatments, but offspring from paired individuals grew faster than those from isolated individuals. On the whole, the self-fertilization depression was extremely low in both populations. Another important result is that paired G1individuals began laying (selfed) eggs several weeks prior to initiating copulation: this is the first characterization of prior selfing (selfing initiated prior to any outcrossing) in a hermaphroditic animal. A significant population effect was observed on most traits studied. Our results are discussed with regard to the maintenance of low outcrossing rates in highly inbreeding species.

Use of the dart apparatus by the hermaphroditic land snail Polymita muscarum (Lea, 1834)

Many species of pulmonate land snails are equipped with one or more so-called "love darts". Even though the number and shape of these calcareous darts vary considerably between species, dart use has only been investigated in very few species. Here, we redescribe the mating behaviour of Polymita muscarum because previous reports did not include the use of the dart apparatus. Mating in this hermaphroditic land snail can be divided into three stages: courtship, copulation and post-copulatory activity. During courtship, full eversion of the genital atrium is reached, thus exposing the sensitive zone, genital lobes and dart apparatus. We observed that P. muscarum pushes the everted dart apparatus repeatedly onto different parts of the partner's body and does not lose its dart after stabbing. Dissected specimens had a single, slender dart with a round base, a broad corona and a circular cross-section. We propose that the morphology of P. muscarum 's dart is consistent with the idea of simple darts needing to be stabbed more often in order to increase the transfer of mucus, which contains a biologically active substance (i.e. allohormone) that enhances the chances of paternity. Besides adding to the growing diversity in the use of love darts in land snails, these findings contribute to the understanding of the evolution of this peculiar reproductive act.