Effects of female postmating odour on male sexual behaviour, in Heliconius butterflies /

The effects of the female postmating odour on male sexual behaviour were examined in Heliconius erato and H. charithonia (Lepidoptera: Nymphalidae). Predictions from the antiaphrodisiac hypothesis were tested using the two reproductive strategies of these species. Within the pupal mating strategy, results from behavioural experiments quantified and statistically tested dispersal rates of pupal-perched males to the presence of stimuli with and without the postmating odour. Results do not support an antiaphrodisiac function to the postmating odour. Similarly, within the adult courtship strategy, behavioural test results indicate that males do not alter their expenditure of energy in terms of either the duration or frequency of courtship behaviours elicited by females with and without the postmating odour. The data from both experiments did not support the antiaphrodisiac hypothesis for the function of the female postmating odour. A novel hypothesis predicting that the postmating female odour acts as an oviposition-deterring pheromone is presented.

Without women: Masculinities, gay male sexual culture and sexual behaviors in Miami, Florida

Recent studies have reported alarmingly high rates of HIV infection and risky sexual behaviors among gay men in Miami, Florida. Previous research has suggested that the risky sexual behaviors of many gay men reflect the pursuit of intimacy and love, and that barriers to intimate relationships among gay men may stem from traditional masculinity norms. This dissertation examines the meanings which gay men ascribe to their sexual behaviors, as well as the intersections of those meanings with both traditional masculinity constructions and Miami's gay male sexual culture. ^ The study is based upon participant observation, print media content analysis, surveys and ethnographic interviews of a purposive snowball sample of 30 Cuban American, Puerto Rican, African American and Anglo gay men who reside in Miami-Dade County, Florida. Analysis of research questions was accomplished through grounded theory methods and descriptive and non-parametric statistics, including Pearson chi-square, Fisher's Exact and Mann-Whitney U tests. ^ The study shows that culturally-specified masculinity norms vary in the relative importance ascribed to heterosexual prowess, economic providership and competitiveness. These cultural differences appear important not only to the timing of sexual awareness and to the strength of homosexual stereotyping as effeminacy, but also to men's strategies in coming out as gay. The meanings men attributed to their sexual behaviors were, however, constructed in response to both inherited masculinity norms and the hypermasculine structure of Miami's gay male sexual culture. In addition to providing an ethnographic account of this subculture, the study elaborates men's issues relative to casual sex and committed relationships. Unprotected anal intercourse with casual partners during the previous twelve months was associated with growing up without one's father in the home, having been teased for effeminacy during childhood, being defensive about one's masculinity, not trusting men, having been cheated on by boyfriends, and believing that long-term gay male relationships are problematic. ^ It is concluded that the continuing epidemic of HIV infections among local gay men, as well as the hypermasculine form of the gay sexual subculture itself, are nihilistic symptoms embedded in the masculinist gender structure of the larger society. ^

Regulation of male sexual development by Sry and Sox9

Sry, a gene from the Y chromosome, is known to initiate testis formation and subsequent male differentiation in mammals. A related gene, Sox9, also plays a critical role in testis determination, possibly in all vertebrates. A number of models have been presented regarding the molecular modes of action of these two genes. However, details regarding their regulation, regulatory target genes, and interacting protein factors and co-factors have not been established with any certainty. In this review, we examine new evidence and re-examine existing evidence bearing on these issues, in an effort to build up an integrative model of the network of gene activity centred around Sry and Sox9. J. Exp. Zool. 290:463-474, 2001. (C) 2001 Wiley-Liss, Inc.

Troubles sexuels masculins et obésité [Male sexual dysfunction and obesity].

Obesity concerns more than 200 million people in the world, with an increasing prevalence in western countries. It is closely related to multiple medical conditions, such as diabetes and hypertension. It was recently shown that testosterone deficiency syndrome and erectile dysfunction (ED) are also linked to male obesity. In this group of patients, ED may be due to defects in corpus cavernosum relaxation, endocrine modifications and nerve signal alterations. Weight loss and increased physical activities can improve erectile function in 30% of obese patients. Additional medical treatments of ED enhance erectile function in more than 80% of patients. Self image improvement associated with appropriate erectile dysfunction medical treatment allow better sexual life and potentially increased motivation for weight loss.

Alpha1-adrenoceptors are required for normal male sexual function.

BACKGROUND AND PURPOSE: Alpha(1)-adrenoceptor antagonists are extensively used in the treatment of hypertension and lower urinary tract symptoms associated with benign prostatic hyperplasia. Among the side effects, ejaculatory dysfunction occurs more frequently with drugs that are relatively selective for alpha(1A)-adrenoceptors compared with other drugs of this class. This suggests that alpha(1A)-adrenoceptors may contribute to ejaculation. However, this has not been studied at the molecular level. EXPERIMENTAL APPROACH: The physiological contribution of each alpha(1)-adrenoceptor subtype was characterized using alpha(1)-adrenoceptor subtype-selective knockout (KO) mice (alpha(1A)-, alpha(1B)- and alpha(1D)-AR KO mice) since the subtype-specific drugs available are only moderately selective. We analysed the role of alpha(1)-adrenoceptors in the blood pressure and vascular response as well as ejaculation by determining these variables in alpha(1)-adrenoceptor subtype-selective KO mice and in mice with all their alpha(1)-adrenoceptor subtypes deleted (alpha(1)-AR triple-KO mice). KEY RESULTS: The pregnancy rate was reduced by 50% in alpha(1A)-adrenoceptor KO mice, and this reduction was dramatically enhanced in alpha(1)-adrenoceptor triple-KO mice. Contractile tension of the vas deferens in response to noradrenaline was markedly decreased in alpha(1A)-adrenoceptor KO mice, and this contraction was completely abolished in alpha(1)-adrenoceptor triple-KO mice. This attenuation of contractility was also observed in the electrically stimulated vas deferens. CONCLUSIONS AND IMPLICATIONS: These results demonstrate that alpha(1)-adrenoceptors, particularly alpha(1A)-adrenoceptors, are required for normal contractility of the vas deferens and consequent sperm ejaculation as well as having a function in fertility.

Why boys will be boys: two pathways of fetal testicular androgen biosynthesis are needed for male sexual differentiation

Human sexual determination is initiated by a cascade of genes that lead to the development of the fetal gonad. Whereas development of the female external genitalia does not require fetal ovarian hormones, male genital development requires the action of testicular testosterone and its more potent derivative dihydrotestosterone (DHT). The "classic" biosynthetic pathway from cholesterol to testosterone in the testis and the subsequent conversion of testosterone to DHT in genital skin is well established. Recently, an alternative pathway leading to DHT has been described in marsupials, but its potential importance to human development is unclear. AKR1C2 is an enzyme that participates in the alternative but not the classic pathway. Using a candidate gene approach, we identified AKR1C2 mutations with sex-limited recessive inheritance in four 46,XY individuals with disordered sexual development (DSD). Analysis of the inheritance of microsatellite markers excluded other candidate loci. Affected individuals had moderate to severe undervirilization at birth; when recreated by site-directed mutagenesis and expressed in bacteria, the mutant AKR1C2 had diminished but not absent catalytic activities. The 46,XY DSD individuals also carry a mutation causing aberrant splicing in AKR1C4, which encodes an enzyme with similar activity. This suggests a mode of inheritance where the severity of the developmental defect depends on the number of mutations in the two genes. An unrelated 46,XY DSD patient carried AKR1C2 mutations on both alleles, confirming the essential role of AKR1C2 and corroborating the hypothesis that both the classic and alternative pathways of testicular androgen biosynthesis are needed for normal human male sexual differentiation.

Of marsupials and men: "Backdoor" dihydrotestosterone synthesis in male sexual differentiation

Following development of the fetal bipotential gonad into a testis, male genital differentiation requires testicular androgens. Fetal Leydig cells produce testosterone that is converted to dihydrotestosterone in genital skin, resulting in labio-scrotal fusion. An alternative 'backdoor' pathway of dihydrotestosterone synthesis that bypasses testosterone has been described in marsupials, but its relevance to human biology has been uncertain. The classic and backdoor pathways share many enzymes, but a 3α-reductase, AKR1C2, is unique to the backdoor pathway. Human AKR1C2 mutations cause disordered sexual differentiation, lending weight to the idea that both pathways are required for normal human male genital development. These observations indicate that fetal dihydrotestosterone acts both as a hormone and as a paracrine factor, substantially revising the classic paradigm for fetal male sexual development.

The makings of maleness: towards an integrated view of male sexual development

As the mammalian embryo develops, it must engage one of the two distinct programmes of gene activity, morphogenesis and organogenesis that characterize males and females. In males, sexual development hinges on testis determination and differentiation, but also involves many coordinated transcriptional, signalling and endocrine networks that underpin the masculinization of other organs and tissues, including the brain. Here we bring together current knowledge about these networks, identify gaps in the overall picture, and highlight the known defects that lead to disorders of male sexual development.

Fecal androgen levels in common marmoset (Callithrix jacchus) males living in captive family groups

In captive common marmoset groups, the reproductive inhibition observed in subordinate female seems to be a result of olfactory, visual and behavioral cues from the dominant female. However, few studies have examined the relationship among adult males living in the same social group. These studies have shown that reproductive failure among peer males seems to be based on hormonal and behavioral mechanisms. New insights on sexual strategies in primates have been shown using fecal steroids, but so far no information is available for common marmoset males. In the present study, we evaluated the influence of light-dark cycle, age and reproductive condition on the profile of fecal androgens in males living in the same family group. Feces were collected from six fathers and six sons for androgen determination during the light phase of the 24-h cycle for eight days randomly distributed over a 4-week period. Androgen levels were determined by enzyme immunoassay technique. Adult sons showed higher androgen levels (166.97 ± 22.95 ng/g) than fathers (80.69 ± 44.38 ng/g) and juveniles (49.06 ± 23.15 ng/g; P < 0.05). No diurnal variation (P > 0.05) in fecal androgen profile was observed in adults or juveniles. No indication of androgen-mediated social competition between fathers and adult sons was demonstrable. These results provide basic information on fecal androgen profile useful to investigate the socioendocrinology of free-ranging common marmoset males and verify that, in contrast to daughters, the reproductive suppression of sons is not based on physiological inhibition of their gonads.

Prenatal Lipopolysaccharide Exposure Affects Maternal Behavior and Male Offspring Sexual Behavior in Adulthood

Objective: This study investigates the effects of prenatal lipopolysaccharide (LPS) exposure on the maternal behavior of pregnant rats and the physical development and sexual behavior of their male offspring in adulthood. Methods: For two experiments, pregnant rats were injected with LPS (250 mu g/kg, i.p.) on gestation day (GD) 21. In the first experiment, the maternal behavior (postnatal day, PND, 6) and the dam`s open-field general activity (PND7) were evaluated. In the second experiment, the maternal pre- and postnatal parameters, the pup`s development, the offspring`s sexual behavior in adulthood, and the pup`s organ weights were assessed. Results: Compared to the control group, the LPS-treated dams presented reduced maternal behavior, decreased general activity, a smaller body weight difference between GD21 and PND1, a greater number of perinatal deaths, and smaller litters. For the male pups, LPS treatment resulted in a decreased body weight on PND2, whereas the anogenital distance and the day of testis descent were not modified. The male sexual behavior was impaired by prenatal LPS. Particularly the number of ejaculating animals was reduced. The testis weight was also lower in the prenatally LPS-treated rats than in the control rats. Conclusion: We propose that prenatal LPS exposure on GD21 acts as an imprinting factor that interferes with the programming of brain sexual determination in offspring. Copyright (C) 2009 S. Karger AG, Basel

Ivermectin impairs sexual behavior in sexually naive, but not sexually experienced male rats

Ivermectin (IVM) is an antiparasitic drug, widely used in domestic animals. In mammals, IVM act as a GABA agonist. This neurotransmitter has an important role in the regulation of sexual behavior. Thus, this study sought to investigate the effects of various medically relevant doses IVM on the sexual behavior of male rats. In particular, we also wished to examine if previous sexual experience modulated responses to IVM. In the first experiment, the sexual behavior of inexperienced male rats was analyzed after they received 0.2, 0.6, 1.0 or 2.0 mg/kg IVM, 15 mm prior to behavioral testing. In the second experiment, the effects of four previous sexual experiences on IVM treated rats (1.0 or 2.0 mg/kg, 15 min prior to the 5th session) were assessed. The standard therapeutic dose (0.2 mg/kg) did not impair the sexual behavior of inexperienced male rats. At a more concentrated dose (0.6 mg/kg), which is still within the therapeutic range, the appetitive phase of sexual behavior of inexperienced male rats was impaired. Likewise, 1.0 mg/kg impaired the appetitive phase. Previous sexual experience blocked almost entirely this sexual impairment, suggesting that previous sexual experience exerts a positive effect in attenuating the sexual impairment produced by IVM treatment. Therefore, the standard therapeutic dose of IVM can be used without producing side effects on sexual behavior. Use of more concentrated therapeutic doses is not recommended during reproductive periods, unless the animals have had previous sexual experience. (C) 2010 Elsevier Ltd. All rights reserved.

Sexual behavior and fertility of male rats submitted to prolonged immobilization-induced stress

In order to investigate whether prolonged stress interferes with the onset of sexual behavior at puberty and with fertility at adulthood, prepubertal male Wistar rats (40 days of age) were immobilized 6 h a day for 15 days (up to early puberty) or for 60 days (until sexual maturity). Pubertal stressed rats showed a two-fold increase in the latency for the first mount (probably due to repeated aversive experience in which a change of environment was always followed by immobilization) and a 2.5-fold increase in the frequency of thrusting (indicative of enhanced sexual performance). The apparently stimulatory effect of prolonged stress on the onset of sexual behavior is discussed in terms of increased testosterone level and interference with the complex interchanges between the neurotransmitters/neuropeptides involved in the central control of male sexual activity. Adult stressed animals were mated with normal females, which became pregnant but exhibited a more than two-fold increase in both pre-implantation and post-implantation loss, probably due to a smaller rate of fertilization and/or fertilization with damaged spermatozoa.

Individual differences and factors affecting male behaviour in field crickets

Individual differences in male sexual behav~our and the factors influencing calling behaviour were studied in the field crickets Gryllus 2 integer and Q. veletis. In a large (13m) outdoor arena individually numbered adult male ~~ integer started calling at three to five days of age but thereafter the age of individual G. integer males did not affect nightly calling duration. Calling also did not correlate with individual weight. In this study individual male calling was continuously distributed from 0 hrs. per night to 3.5 hrs. per night, on average. A temporal effect on the number of G. integer males calling was observed. The number of males calling through the night was uniform, but a sharp increase in the number calling was observed in the early morning. No difference in calling times was observed between the night and dawn callers. AlsC)' males calling at dawn usually didnotc'all during the preceeding night. Calling and reproductive success in 1979 demonstrated a negative logarithmic relationship while in the 1980(initial) population a negative linear relationship was observed. No relationship was seen in the 1980 high density population. The ratio of non-callers to callers also affected the mating of individuals in the 1979 and1980(initial) densities:-non~callers (males calling .5 hrs. per night, on average, or less) obtained more females when the population contained a high number of callers, this being a negative logarithmic relationship to, No such relationship was observed in the 1980 high density population. Individual displacement varied nightly and was not correlated to amount of calling or reproductive success of individual G. integer males. G. integer males were displa~ed more when in a higher density in the outdoor arena Male G. integer and G. veletis behaviours were also observed in an indoor arena at different densities and, in G. veletis, with respect to female presence. When females were present in the arena, in G. veletis, male calling was reduced. Males of both species called less, on average, when in ~ higher density, than when they were in a lower density. Male displacement of both species increased on average when in a higher density as compared to displacement in a lower density. Aggression was measured by aggressive call-ing and fighting and was studied in regards to density.G. integer demonstrated less aggression in all but one comparison at higher density. No difference was observed in the ratio of aggressive calling to f.ighting comparison in G. integer. G. veletis demonstrated mixed results. No difference in aggression between densities was observed in comparisons. Less.aggression did occur in higher densities when comparisons invol.ved fighting behaviour. Male behaviour represents a competitive strategy against ot~er males, strategy being defined as a genetic (in part) alternative to other strategies. In this sense, the factors of time, density, male-male aggression, and female presence are conditions demonstrated to affect male behaviour in G. integer and G. veletis. Individual male differences and other considerations suggest that alternative male behaviours are represented by at least two conditional strategies. This possibility, and the transient 'or stable nature of genetic polymorphisms in field cricket behaviour are considered.