Kim Wallen

Summary of the recommendations on sexual dysfunctions in men

INTRODUCTION Sexual health is an integral part of overall health. Sexual dysfunction can have a major impact on quality of life and psychosocial and emotional well-being. AIM To provide evidence-based, expert-opinion consensus guidelines for clinical management of sexual dysfunction in men. METHODS An international consultation collaborating with major urologic and sexual medicine societies convened in Paris, July 2009. More than 190 multidisciplinary experts from 33 countries were assembled into 25 consultation committees. Committee members established scope and objectives for each chapter. Following an exhaustive review of available data and publications, committees developed evidence-based guidelines in each area. Main Outcome Measures.  New algorithms and guidelines for assessment and treatment of sexual dysfunctions were developed based on work of previous consultations and evidence from scientific literature published from 2003 to 2009. The Oxford system of evidence-based review was systematically applied. Expert opinion was based on systematic grading of medical literature, and cultural and ethical considerations. RESULTS Algorithms, recommendations, and guidelines for sexual dysfunction in men are presented. These guidelines were developed in an evidence-based, patient-centered, multidisciplinary manner. It was felt that all sexual dysfunctions should be evaluated and managed following a uniform strategy, thus the International Consultation of Sexual Medicine (ICSM-5) developed a stepwise diagnostic and treatment algorithm for sexual dysfunction. The main goal of ICSM-5 is to unmask the underlying etiology and/or indicate appropriate treatment options according to mens and womens individual needs (patient-centered medicine) using the best available data from population-based research (evidence-based medicine). Specific evaluation, treatment guidelines, and algorithms were developed for every sexual dysfunction in men, including erectile dysfunction; disorders of libido, orgasm, and ejaculation; Peyronies disease; and priapism. CONCLUSIONS Sexual dysfunction in men represents a group of common medical conditions that need to be managed from a multidisciplinary perspective.

Men and women differ in amygdala response to visual sexual stimuli

Men are generally more interested in and responsive to visual sexually arousing stimuli than are women. Here we used functional magnetic resonance imaging (fMRI) to show that the amygdala and hypothalamus are more strongly activated in men than in women when viewing identical sexual stimuli. This was true even when women reported greater arousal. Sex differences were specific to the sexual nature of the stimuli, were restricted primarily to limbic regions, and were larger in the left amygdala than the right amygdala. Men and women showed similar activation patterns across multiple brain regions, including ventral striatal regions involved in reward. Our findings indicate that the amygdala mediates sex differences in responsiveness to appetitive and biologically salient stimuli; the human amygdala may also mediate the reportedly greater role of visual stimuli in male sexual behavior, paralleling prior animal findings.

Sex and context: Hormones and primate sexual motivation.

Gonadal hormones regulate the ability to copulate in most mammalian species, but not in primates because copulatory ability has been emancipated from hormonal control. Instead, gonadal hormones primarily influence sexual motivation. This separation of mating ability from hormonally modulated mating interest allows social experience and context to powerfully influence the expression of sexual behavior in nonhuman primates, both developmentally and in adulthood. For example, male rhesus monkeys mount males and females equally as juveniles, but mount females almost exclusively as adults. Having ejaculated with a female better predicted this transition to female mounting partners than did increased pubertal testosterone (T). It is proposed that increased pubertal T stimulates male sexual motivation, increasing the males probability of sexual experience with females, ultimately producing a sexual preference for females. Eliminating T in adulthood reduces male sexual motivation in both humans and rhesus monkeys, but does not eliminate the capacity to engage in sex. In male rhesus monkeys the effects of reduced androgens on sexual behavior vary with social status and sexual experience. Human sexual behavior also varies with hormonal state, social context, and cultural conventions. Ovarian hormones influence female sexual desire, but the specific sexual behaviors engaged in are affected by perceived pregnancy risk, suggesting that cognition plays an important role in human sexual behavior. How the physical capacity to mate became emancipated from hormonal regulation in primates is not understood. This emancipation, however, increases the importance of motivational systems and results in primate sexual behavior being strongly influenced by social context.

Nature Needs Nurture: The Interaction of Hormonal and Social Influences on the Development of Behavioral Sex Differences in Rhesus Monkeys☆

Thirty years of research on early social and hormonal environments and their relationship to the expression of behavioral sex differences in rhesus monkeys are reviewed. These studies demonstrate that whether aggressive and submissive behaviors are sexually dimorphic depends primarily on the social and not the hormonal environment. Early rearing environments without mothers or allowing brief periods of peer interaction produced higher levels of male aggression and female submission. Presenting behavior was expressed more by females than males in environments with high male aggressivity and female submissiveness. No sex differences in presenting occurred in low aggressivity environments, unless monkeys were reared isosexually, when males presented more than females. Rough and tumble play and foot-clasp mounting were consistently exhibited more by males than females across all rearing environments studied, but rearing environment affected the degree of the sex difference. When reared isosexually males displayed less, and females more, foot-clasp mounting than when heterosexually reared. No social environment increased the low frequency of female rough and tumble play. Suppressing neonatal androgen in males did not effect any sexually dimorphic behavior. Prenatal androgen administration to genetic females masculinized many aspects of their juvenile behavior, consistently increasing rough and tumble play and foot-clasp mounting across different social environments. Thus the sexually dimorphic behaviors which showed the smallest variability across social contexts were the most profoundly affected by the prenatal hormonal environment. These studies demonstrate that the expression of consistent juvenile behavioral sex differences results from hormonally induced predispositions to engage in specific patterns of juvenile behavior whose expression is shaped by the specific social environment experienced by the developing monkey.

Desire and ability: Hormones and the regulation of female sexual behavior

The distinction between the ability to copulate and the desire to copulate is used to understand species differences in hormonal regulation of female sexual behavior. Evidence is presented demonstrating that ovarian hormones modulate female sexual motivation in both rodent and primate females. The thesis is developed that rodent females differ from primate females primarily in their dependence upon hormones for the ability to mate. Thus, apparent differences between the two groups of females in the extent to which hormones control copulatory behavior does not stem from differences in hormonal regulation of female sexual motivation but from the physical ability of primate, but not rodent, females to mate without hormonal stimulation. This emancipation of the ability to copulate from hormonal influence makes female sexual motivation the primary regulator of mating in primates. Dependence upon female sexual motivation means that the copulatory behavior of primate females is easily influenced by their physical and social environment. Because primate females can mate without hormonal input, female sexual initiation, not copulation, is argued to be the only valid indicator of female sexual motivation.

Sex differences in viewing sexual stimuli: An eye-tracking study in men and women

Men and women exhibit different neural, genital, and subjective arousal responses to visual sexual stimuli. The source of these sex differences is unknown. We hypothesized that men and women look differently at sexual stimuli, resulting in different responses. We used eye tracking to measure looking by 15 male and 30 female (15 normal cycling (NC) and 15 oral contracepting (OC)) heterosexual adults viewing sexually explicit photos. NC Women were tested during their menstrual, periovulatory, and luteal phases while Men and OC Women were tested at equivalent intervals, producing three test sessions per individual. Men, NC, and OC Women differed in the relative amounts of first looks towards, percent time looking at, and probability of looking at, defined regions of the pictures. Men spent more time, and had a higher probability of, looking at female faces. NC Women had more first looks towards, spent more time, and had a higher probability of, looking at genitals. OC Women spent more time, and had a higher probability of, looking at contextual regions of pictures, those featuring clothing or background. Groups did not differ in looking at the female body. Menstrual cycle phase did not affect womens looking patterns. However, differences between OC and NC groups suggest hormonal influences on attention to sexual stimuli that were unexplained by subject characteristic differences. Our finding that men and women attend to different aspects of the same visual sexual stimuli could reflect pre-existing cognitive biases that possibly contribute to sex differences in neural, subjective, and physiological arousal.

Sex differences in rhesus monkey toy preferences parallel those of children

Sex differences in toy preferences in children are marked, with boys expressing stronger and more rigid toy preferences than girls, whose preferences are more flexible. Socialization processes, parents, or peers encouraging play with gender-specific toys are thought to be the primary force shaping sex differences in toy preference. A contrast in view is that toy preferences reflect biologically-determined preferences for specific activities facilitated by specific toys. Sex differences in juvenile activities, such as rough-and-tumble play, peer preferences, and infant interest, share similarities in humans and monkeys. Thus if activity preferences shape toy preferences, male and female monkeys may show toy preferences similar to those seen in boys and girls. We compared the interactions of 34 rhesus monkeys, living within a 135 monkey troop, with human wheeled toys and plush toys. Male monkeys, like boys, showed consistent and strong preferences for wheeled toys, while female monkeys, like girls, showed greater variability in preferences. Thus, the magnitude of preference for wheeled over plush toys differed significantly between males and females. The similarities to human findings demonstrate that such preferences can develop without explicit gendered socialization. We offer the hypothesis that toy preferences reflect hormonally influenced behavioral and cognitive biases which are sculpted by social processes into the sex differences seen in monkeys and humans.

Masculinization and Defeminization in Altricial and Precocial Mammals: Comparative Aspects of Steroid Hormone Action

Publisher Summary This chapter provides evidence that this distinction may have heuristic value in understanding the nature of steroidal influences on masculinization and defeminization. Across both types of mammals, defeminization was found to utilize estrogenic metabolites of androgens. However, the evidence of this requirement was stronger in altricial than precocial species. Unambiguous evidence of defeminization by nonaromatizable androgens was found only in the precocial rhesus monkey. The role of aromatization in masculinization was less clear, with little evidence in any species that mounting potential differentiated under either androgenic or estrogenic influence. When all aspects of male sexual and social behavior were considered, altricial species relied more on aromatization for masculinization than precocial species. No evidence was found in human males that the actions of estrogenic compounds were necessary for normal male sexual differentiation. These apparent differences between altricial and precocial species in the hormonal actions producing masculinization and defeminization might be an artifact of which species have become favored laboratory subjects.

Periovulatory changes in female sexual behavior and patterns of ovarian steroid secretion in group-living rhesus monkeys

The behavior of nine intact group-living adult female rhesus was observed for 30 min daily with each of four adult male rhesus across a verified ovulatory menstrual cycle. Blood samples collected from females daily or on alternate days were analyzed for estradiol, testosterone, and progesterone. Female patterns of approach, follow, and initiate proximity increased several days prior to the estradiol peak, peaked on the day of the estradiol peak, then declined completely or to very low frequencies. Mounts, intromissions, and ejaculations increased significantly on the day of the estradiol peak, remained elevated for 2 more days, then declined completely by the fifth day after peak estradiol. Ejaculations never occurred outside of a 10-day period starting 4 days before the estradiol peak and ending 5 days after the estradiol peak. During this period females initiated over 90% of all approaches. Female hand slap, threaten away, and stand up increased significantly on the first day of increased copulation, remained elevated while copulation was significantly elevated, then decreased along with the decline in copulation. Ten of eleven patterns of female behavior correlated significantly with estradiol level prior to the estradiol peak. All were significantly inversely correlated with progesterone level after the estradiol peak. No pattern of female behavior correlated significantly with testosterone either before or after the estradiol peak. Similarly, male patterns of behavior correlated with female levels of estradiol and progesterone, but not testosterone. These results demonstrate a relationship between increased serum estradiol and increased female initiation of sexual behavior. The finding that some patterns of female behavior increase several days prior to copulation, whereas other behaviors increase coincident with increased copulation suggests that the behavior of group-living rhesus females serves two functions. The first is to communicate sexual interest and the second is to maintain the consort pair and increase the probability that ejaculation will occur. In addition, the strong correlation between preovulatory female behavior and estradiol level suggests that the females behavior provides precise information about her reproductive state and could thus coordinate copulation with maximal fertility.

Timing of Prenatal Androgen Exposure: Anatomical and Endocrine Effects on Juvenile Male and Female Rhesus Monkeys

Prenatal androgen shapes genital differentiation. In humans, genital anatomy determines sex of rearing and subsequent behavioral development. Rhesus monkey genital anatomy and neuroendocrine function are sexually differentiated, and behavioral development occurs in a complex social environment. We investigated prenatal hormonal influences on sexual differentiation by suppressing or increasing androgens in male and female rhesus monkeys. Pregnant multiparous female rhesus monkeys received 35-40 days of testosterone enanthate (TE) treatment, androgen antagonist (flutamide, FL) treatment, or vehicle starting on gestation day (GD) 35 or 40 (early) or GD 110 or 115 (late). Exogenous androgen increased neonatal LH secretion in females when given early and altered female genital differentiation when administered either early or late. TE treatment, early or late in gestation, had no measurable effects on male genital differentiation or neuroendocrine function. Early FL treatment, however, radically altered male genital differentiation, producing in two cases males with a urethral opening separate from the glans. In females, early FL treatment produced detectable alterations in genitalia consistent with a reduced exposure to prenatal androgen, suggesting that female rhesus monkeys are naturally exposed prenatally to meaningful levels of T. Late FL treatment reduced male penis size and increased neonatal T secretion, but had no effect in females. This is the first study to block endogenous prenatal testosterone in rhesus monkeys, thereby altering sexual differentiation. These findings illustrate the complexity of prenatal influences on anatomical and neuroendocrine development. The relationship between the anatomical changes reported here and sex differences in behavior is currently under investigation.