Prenatal testosterone and gender-related behaviour

Age- and Sex-Dependent Changes in Androgen Receptor Expression in the Developing Mouse Cortex and Hippocampus

During the perinatal period, male mice are exposed to higher levels of testosterone (T) than females, which promotes sexual dimorphism in their brain structures and behaviors. In addition to acting via estrogen receptors after being locally converted into estradiol by aromatase, T also acts directly through androgen receptor (AR) in the brain. Therefore, we hypothesized that AR expression in the developing mouse cortex and hippocampus was sexually dimorphic. To test our hypothesis, we measured and determined AR mRNA and protein levels in mouse cortex/hippocampus collected on the day of birth (PN0) and 7 (PN7), 14 (PN14), and 21 (PN21) days after birth. We demonstrated that, as age advanced, AR mRNA levels increased in the cortex/hippocampus of both sexes but showed no sex difference. Two AR proteins, the full-length (110 kDa) and a smaller isoform (70 kDa), were detected in the developing mouse cortex/hippocampus with an age-dependent increase in protein levels of both AR isoforms at PN21 and a transient masculine increase in expression of the full-length AR protein on PN7. Thus, we conclude that the postnatal age and sex differences in AR protein expression in combination with the sex differences in circulating T may cause sexual differentiation of the mouse cortex/hippocampus.

Feminists wrestle with testosterone: hormones, socialization and cultural interactionism as predictors of women's gendered selves

Sociology of gender has developed beyond a personality-centered idea of "sex-roles" to an approach that stresses interaction and social structure. At the same time, there has been a concurrent development in the psychological sex-differences and medical literatures toward including the biological bases of sex-typed behavior and gender identities. In this paper, while we conceptualize gender as a social structure, we focus only on the individual level of analysis: testing the relative strength of (maternal circulating) prenatal hormones, childhood socialization, and the power of expectations attached to adult social roles (cultural interactionist) as explanations for women's self-reported feminine and masculine selves. Our findings are complex, and support some importance of each theory. Prenatal hormones, childhood socialization, and cultural interactionism were all influential factors for gendered selves. While cultural expectations predicted only feminine selves, prenatal hormones were more robust predictors of masculine sense of self. While personality may be a relatively stable characteristic influenced by the body and childhood socialization, our results reinforce the importance of studying how the social world responds to and reinforces gendered personality.

Facial masculinity: how the choice of measurement method enables to detect its influence on behaviour

Recent research has explored the relationship between facial masculinity, human male behaviour and males' perceived features (i.e. attractiveness). The methods of measurement of facial masculinity employed in the literature are quite diverse. In the present paper, we use several methods of measuring facial masculinity to study the effect of this feature on risk attitudes and trustworthiness. We employ two strategic interactions to measure these two traits, a first-price auction and a trust game. We find that facial width-to-height ratio is the best predictor of trustworthiness, and that measures of masculinity which use Geometric Morphometrics are the best suited to link masculinity and bidding behaviour. However, we observe that the link between masculinity and bidding in the first-price auction might be driven by competitiveness and not by risk aversion only. Finally, we test the relationship between facial measures of masculinity and perceived masculinity. As a conclusion, we suggest that researchers in the field should measure masculinity using one of these methods in order to obtain comparable results. We also encourage researchers to revise the existing literature on this topic following these measurement methods.

Testosterone and its effects on human male adolescent mood and behavior: a systematic review

PURPOSE

During human puberty, there is an approximate 30-fold increase in testosterone production in boys. This increase is often linked to changes in mood and behavior in adolescence such as aggression, an increase in risk taking, and depression. The aim of this systematic review was to determine what evidence exists on the effects of endogenous testosterone on behavior and mood in males during adolescence.

METHODS

The following databases were searched: MEDLINE, Pre-MEDLINE, Education Resources Information Centre, PsycINFO, EMBASE, Scopus, and Web of Science. Only human studies were included. The study is community based, and the participants were healthy male adolescents within the age range of 9-18 years. Studies were required to have a validated mood and/or behavior assessment contemporaneous with a timed testosterone measurement.

RESULTS

A total of 27 studies met the inclusion criteria of which only one was a longitudinal study. The remaining 26 studies were cross sectional in their analysis. As a variety of measurement tools were used, no meta-analysis was possible. Most studies focused on aggression. The one longitudinal study looking at testosterone and aggression showed little relationship with concurrent changes in aggression. Most of the cross-sectional studies of adolescent males observed relationships between aggression and testosterone levels. With respect to other behaviors and moods and/or affect, no consistent relationships with testosterone were observed in cross-sectional studies.

CONCLUSIONS

This systematic review concludes that there are insufficient longitudinal data of high methodological quality to currently confirm that changing testosterone levels during puberty are significantly associated with mood and behavior in adolescent males. To discount these findings is to risk apportioning blame inappropriately and missing other important diagnoses in adolescent males.

Sex differences in anxiety and depression clinical perspectives

Sex differences are prominent in mood and anxiety disorders and may provide a window into mechanisms of onset and maintenance of affective disturbances in both men and women. With the plethora of sex differences in brain structure, function, and stress responsivity, as well as differences in exposure to reproductive hormones, social expectations and experiences, the challenge is to understand which sex differences are relevant to affective illness. This review will focus on clinical aspects of sex differences in affective disorders including the emergence of sex differences across developmental stages and the impact of reproductive events. Biological, cultural, and experiential factors that may underlie sex differences in the phenomenology of mood and anxiety disorders are discussed.

Nonadherence with ambulatory saliva sampling is associated with biased salivary testosterone estimates

OBJECTIVE

Nonadherence with scheduled saliva sampling, as encountered in ambulatory settings, can bias the estimation of salivary cortisol concentrations. This study is the first to estimate if such nonadherence is also associated with biased salivary testosterone concentration estimates.

METHODS

Using a standard ambulatory saliva-sampling protocol, we instructed pregnant women to collect saliva samples on two consecutive days at awakening, 1100h, 1500h, 2000h, and 2200h. We estimated testosterone concentrations in the saliva samples and participants' actual sampling times with an electronic medication event-monitoring system. We classified a saliva sample as adherent if it was sampled within a specific time window relative to its scheduled sampling time. We used a mixed-model analysis to distinguish between trait (number of adherent saliva samples per participant) and state (adherence status of a specific sample) adherence.

RESULTS

We included 60 pregnant women in this study. Seventy-five percent (448 of 600) of the scheduled samples indicated adherence with the sampling schedule. Participants' trait adherence was associated with their diurnal profiles of salivary testosterone estimates; that is, adherent participants had higher salivary testosterone estimates compared with nonadherent participants, F(1,58)=5.41, p=0.023, Cohen's d=0.67. The state adherence of a sample was associated with the salivary testosterone estimate of the related sample, F(1,469)=4.48, p=0.035, Cohen's d=0.20, with delayed sampling associated with lower salivary testosterone estimates.

CONCLUSIONS

The results suggest that common ambulatory nonadherence with scheduled saliva sampling is associated with biased salivary testosterone estimates. They will inform further studies estimating salivary testosterone with ambulatory saliva-sampling designs and highlight the relevance of strategies to improve or confirm adherence, beyond routinely used instructions.

Identification of sexually dimorphic genes in the neonatal mouse cortex and hippocampus

The cerebral cortex and hippocampus are important for the control of cognitive functions and social behaviors, many of which are sexually dimorphic and tightly regulated by gonadal steroid hormones via activation of their respective nuclear receptors. As different levels of sex steroid hormones are present between the sexes during early development and their receptors act as transcription factors to regulate gene expression, we hypothesize that sexually dimorphic gene expression in the developing mouse cortex and hippocampus might result in sex differences in brain structures and neural circuits governing distinct behaviors between the sexes as adults. To test our hypothesis, we used gene expression microarrays to identify 90 candidate genes differentially expressed in the neonatal cortex/hippocampus between male and female mice, including 55 male-biased and 35 female-biased genes. Among these genes, sexually dimorphic expression of eight sex chromosome genes was confirmed by reverse transcription with quantitative PCR (RT-qPCR), including three located on the X chromosome (Xist, Eif2s3x, and Kdm6a), three on the Y chromosome (Ddx3y, Eif2s3y, and Kdm5d), and two in the pseudoautosomal region of the X and Y chromosomes (Erdr1 and Mid1). In addition, five autosomal genes (Cd151, Dab2, Klk8, Meg3, and Prkdc) were also validated for their sexually dimorphic expression in the neonatal mouse cortex/hippocampus. Gene Ontology annotation analysis suggests that many of these sexually dimorphic genes are involved in histone modifications, cell proliferation/death, androgen/estrogen signaling pathways, and synaptic organization, and these biological processes have been implicated in differential neural development, cognitive function, and neurological diseases between the sexes.

Postnatal testosterone concentrations and male social development

Converging evidence from over 40 years of behavioral research indicates that higher testicular androgens in prenatal life and at puberty contribute to the masculinization of human behavior. However, the behavioral significance of the transient activation of the hypothalamic-pituitary-gonadal (HPG) axis in early postnatal life remains largely unknown. Although early research on non-human primates indicated that suppression of the postnatal surge in testicular androgens had no measurable effects on the later expression of the male behavioral phenotype, recent research from our laboratory suggests that postnatal testosterone concentrations influence male infant preferences for larger social groups and temperament characteristics associated with the later development of aggression. In later assessment of gender-linked behavior in the second year of life, concentrations of testosterone at 3-4 months of age were unrelated to toy choices and activity levels during toy play. However, higher concentrations of testosterone predicted less vocalization in toddlers and higher parental ratings on an established screening measure for autism spectrum disorder. These findings suggest a role of the transient activation of the HPG axis in the development of typical and atypical male social relations and suggest that it may be useful in future research on the exaggerated rise in testosterone secretion in preterm infants or exposure to hormone disruptors in early postnatal life to include assessment of gender-relevant behavioral outcomes, including childhood disorders with sex-biased prevalence rates.

The effects of prenatal sex steroid hormones on sexual differentiation of the brain

Most of the anatomical, physiological and neurochemical gender-related differences in the brain occur prenatally. The sexual differences in the brain are affected by sex steroid hormones, which play important roles in the differentiation of neuroendocrine system and behavior. Testosterone, estrogen and dihydrotestosterone are the main steroid hormones responsible for the organization and sexual differentiation of brain structures during early development. The structural and behavioral differences in the female and male brains are observed in many animal species; however, these differences are variable between species. Animal and human (in vivo imaging and postmortem) studies on sex differences in the brain have shown many differences in the local distribution of the cortex, the gray-white matter ratio, corpus callosum, anterior commissure, hypothalamus, bed nucleus of the stria terminalis, limbic system and neurotransmitter systems. This review aims to evaluate the anatomical, physiological and neurochemical differences in the female and male brains and to assess the effect of prenatal exposure to sex steroid hormones on the developing brain.

Psychological aspects of the treatment of patients with disorders of sex development

Research on the psychological development of persons with Disorders of Sex Development (DSD) has focused on understanding the influence of atypical sex hormone exposure during steroid-sensitive periods of prenatal brain development on the process of psychosexual differentiation (i.e., gender identity, gender role, and sexual orientation). In contrast, analysis of clinical management strategies has focused on gender assignment and the desirability and timing of genital surgery. This review focuses on the psychological issues that confront clinicians managing the care of persons born with DSD and their families. Particular attention is paid to processes and factors that potentially mediate or moderate psychosocial and psychosexual outcomes within and across developmental stages.

Psychosexual development in adolescents and adults with disorders of sex development--results from the German Clinical Evaluation Study

INTRODUCTION

Both biological and psychosocial factors influence psychosexual development. High levels of pre- and postnatal androgens lead to more male-typical behavior. So far, the influence of androgens on gender identity and sexual orientation is unclear. Disorders of sex development (DSDs) are heterogeneous genetic conditions with different levels of prenatal androgens resulting in variations of genital development. Through DSD, the role of the different factors, especially androgen exposure, on psychosexual development can be evaluated.

AIM

The purpose of the study was to assess psychosexual development in adolescents and adults with different forms of DSD.

METHODS

For the examination of psychosexual development of 66 adolescents and 110 adults with DSD, the authors used the Utrecht Gender Dysphoria Scale for adolescents, the Questionnaire of Gender Identity for adults, and a condition-specific DSD study questionnaire. Individuals were analyzed in four subgroups reflecting the karyotype, absence/presence of androgen effects, and gender of rearing.

MAIN OUTCOME MEASURES

Main outcome measures used were gender identity, friendships, love and sexual relationships, and sexual orientation in adolescents and adults with DSD.

RESULTS

Individuals with DSD did not show increased gender dysphoria. However, partnership and sexuality were identified to be difficult areas of life. Both adolescents and adults with DSD reported fewer experiences regarding love or sexual relationships compared with unaffected individuals. Especially men with DSD and undervirilization and women with DSD and androgen effects less often had a love relationship. Adult women with DSD and androgen effects more frequently engaged in love and sexual relationships with individuals of the same gender compared with women without DSD.

CONCLUSION

Individuals with DSD experience atypical hormonal influences (higher levels of androgens in girls/women and lower levels in androgens in boys/men); however, they did not show increased gender dysphoria in this study. However, partnership and sexual relationships are difficult areas of life for adolescents and adults with DSD. We recommend that individuals with DSD should get support from a multiprofessional team with competency in assessing and counseling issues regarding relationships and sexuality. Contact to other individuals with DSD can be helpful for nonprofessional support and exchange of experiences.

Sex steroids and connectivity in the human brain: a review of neuroimaging studies

Our brain operates by the way of interconnected networks. Connections between brain regions have been extensively studied at a functional and structural level, and impaired connectivity has been postulated as an important pathophysiological mechanism underlying several neuropsychiatric disorders. Yet the neurobiological mechanisms contributing to the development of functional and structural brain connections remain to be poorly understood. Interestingly, animal research has convincingly shown that sex steroid hormones (estrogens, progesterone and testosterone) are critically involved in myelination, forming the basis of white matter connectivity in the central nervous system. To get insights, we reviewed studies into the relation between sex steroid hormones, white matter and functional connectivity in the human brain, measured with neuroimaging. Results suggest that sex hormones organize structural connections, and activate the brain areas they connect. These processes could underlie a better integration of structural and functional communication between brain regions with age. Specifically, ovarian hormones (estradiol and progesterone) may enhance both cortico-cortical and subcortico-cortical functional connectivity, whereas androgens (testosterone) may decrease subcortico-cortical functional connectivity but increase functional connectivity between subcortical brain areas. Therefore, when examining healthy brain development and aging or when investigating possible biological mechanisms of 'brain connectivity' diseases, the contribution of sex steroids should not be ignored.

Gender role behaviour in prenatally dexamethasone-treated children at risk for congenital adrenal hyperplasia--a pilot study

AIM

To investigate the effects of prenatal dexamethasone (DEX) exposure on gender role behaviour.

METHODS

The participants were 25 of the 40 children (62%, mean age 11 years) at risk for CAH treated with DEX prenatally during the years 1985-1995 in Sweden. The control group consisted of 35 sex- and age-matched healthy children. A new inventory, the Karolinska Inventory of Gender Role Behaviour (KI-GRB), was developed to assess directly school-age children's behaviour, and was evaluated using a separate sample of 160 school-age children.

RESULTS

DEX-treated CAH-unaffected boys showed more neutral behaviours than the controls (p = 0.04), while the DEX-treated CAH-unaffected girls did not differ from the controls after adjusting for the site of residence. There was a larger variation in the behaviour of the DEX-treated boys (p < 0.05) and a tendency for less-masculine behaviours in the DEX-treated CAH-unaffected children (p = 0.13). There were no between-group differences in the feminine behaviours. Recalculation of the analyses including the CAH-affected children showed analogous results.

CONCLUSIONS

This pilot study indicates that the gender role behaviour may be affected in boys as an effect of DEX exposure in early pregnancy. Larger retrospective studies are needed for more conclusive results.

Maternal early life factors associated with hormone levels and the risk of having a child with an autism spectrum disorder in the nurses health study II

It is not known whether reproductive factors early in the mother's life influence risk of autism spectrum disorders (ASD). We assessed maternal age at menarche, menstrual cycle characteristics during adolescence, oral contraceptive use prior to first birth, body shape, and body mass index (BMI) in association with ASD using binomial regression in a cohort study of 61,596 women, including 743 cases. Overall, early life factors were not associated with ASD, though early age at menarche (RR for age 10 or less = 1.54, 95% CI 1.18, 2.02, p = 0.0002) and BMI at age 18 of ≥30 (RR 2.03, 95% CI 1.34, 3.08, p = 0.0008) were significantly associated with increased risk of ASD. Further work should investigate the potential influence of these factors.

Effects of short-course androgen therapy on the neurodevelopmental profile of infants and children with 49,XXXXY syndrome

AIM

The aim of this investigation was to ascertain whether an early course of androgen treatment (three injections testosterone enanthate, 25 mg) could have a positive impact on any domains of neurodevelopmental function in boys with 49,XXXXY.

METHODS

A total of 22 boys with a karyotype of 49,XXXXY participated in a multidisciplinary assessment of neurocognition, speech and language, paediatric neurology and endocrinology evaluations. One group had received early androgen and another group did not receive any hormonal treatment prior to the evaluation. The mean age of treatment for Group 1 was 12 months with the mean age of first evaluation 74 months. The mean age of first evaluation for Group 2 was 87 months. Statistical analysis was completed to determine whether there was a positive treatment effect from androgen therapy.

RESULTS

There was a significant positive treatment effect in speech and language domain, gestural communication and vocabulary development. No treatment effect was seen on nonverbal capacities.

CONCLUSION

Our findings revealed improved function in several areas of development which had been severely delayed in boys with 49,XXXXY. Continued research is underway to expand our understanding of the relationship of androgen, brain function and behavioural outcome in boys with 49,XXXXY.

Endocrine disruptors as a threat to neurological function

Endocrine disruption is a concept and principle whose origins can be traced to the beginnings of the environmental movement in the 1960s. It began with puzzlement about and the flaring of research on the decline of wildlife, particularly avian species. The proposed causes accented pesticides, especially persistent organochlorines such as DDT. Its scope gradually widened beyond pesticides, and, as endocrine disruption offered an explanation for the wildlife phenomena, it seemed to explain, as well, changes in fertility and disorders of male reproduction such as testicular cancer. Once disturbed gonadal hormone function became the most likely explanation, it provoked other questions. The most challenging arose because of how critical gonadal hormones are to brain function, especially as determinants of brain sexual differentiation. Pursuit of such connections has generated a robust literature embracing a broad swath of chemical classes. How endocrine disrupting chemicals influence the adult and aging brain is a question, so far mostly ignored because of the emphasis on early development, that warrants vigorous investigation. Gonadal hormones are crucial to optimal brain function during maturity and even senescence. They are pivotal to the processes of neurogenesis. They exert protective actions against neurodegenerative disorders such as dementia and support smoothly functioning cognitive activities. The limited research conducted so far on endocrine disruptors, aging, and neurogenesis argues that they should be overlooked no longer.

Cortical activation during mental rotation in male-to-female and female-to-male transsexuals under hormonal treatment

There is strong evidence of sex differences in mental rotation tasks. Transsexualism is an extreme gender identity disorder in which individuals seek cross-gender treatment to change their sex. The aim of our study was to investigate if male-to-female (MF) and female-to-male (FM) transsexuals receiving cross-sex hormonal treatment have different patterns of cortical activation during a three-dimensional (3D) mental rotation task. An fMRI study was performed using a 3-T scan in a sample of 18 MF and 19 FM under chronic cross-sex hormonal treatment. Twenty-three males and 19 females served as controls. The general pattern of cerebral activation seen while visualizing the rotated and non-rotated figures was similar for all four groups showing strong occipito-parieto-frontal brain activation. However, compared to control males, the activation of MF transsexuals during the task was lower in the superior parietal lobe. Compared to control females, MF transsexuals showed higher activation in orbital and right dorsolateral prefrontal regions and lower activation in the left prefrontal gyrus. FM transsexuals did not differ from either the MF transsexual or control groups. Regression analyses between cerebral activation and the number of months of hormonal treatment showed a significant negative correlation in parietal, occipital and temporal regions in the MF transsexuals. No significant correlations with time were seen in the FM transsexuals. In conclusion, although we did not find a specific pattern of cerebral activation in the FM transsexuals, we have identified a specific pattern of cerebral activation during a mental 3D rotation task in MF transsexuals under cross-sex hormonal treatment that differed from control males in the parietal region and from control females in the orbital prefrontal region. The hypoactivation in MF transsexuals in the parietal region could be due to the hormonal treatment or could reflect a priori cerebral differences between MF transsexual and control subjects.

Should male gender assignment be considered in the markedly virilized patient With 46,XX and congenital adrenal hyperplasia?

PURPOSE

We assess the outcome in 46,XX men with congenital adrenal hyperplasia who were born with Prader 4 or 5 genitalia and assigned male gender at birth.

MATERIALS AND METHODS

After receiving institutional review board approval and subject consent we reviewed the medical records of 12 men 35 to 69 years old with 46,XX congenital adrenal hyperplasia, of whom 6 completed social and gender issue questionnaires.

RESULTS

All subjects were assigned male gender at birth, were diagnosed with virilizing congenital adrenal hyperplasia at age greater than 3 years and indicated a male gender identity with sexual orientation to females. Ten of the 12 subjects had always lived as male and 2 who were reassigned to female gender in childhood subsequently self-reassigned as male. Nine of the 12 men had long-term female partners, including 7 married 12 years or more. The 3 subjects without a long-term female partner included 1 priest, 1 who was reassigned female gender, married, divorced and self-reassigned as male, and 1 with a girlfriend and sexual activity. All except the priest and the subject who was previously married when female indicated a strong libido and frequent orgasmic sexual activity. Responses to self-esteem, masculinity, body image, social adjustment and symptom questionnaires suggested adjustments related to the extent of familial and social support.

CONCLUSIONS

Outcome data on severely masculinized 46,XX patients with congenital adrenal hyperplasia who were assigned male gender at birth indicate male gender identity in adulthood with satisfactory male sexual function in those retaining male genitalia. In men who completed questionnaires results were poorer in those lacking familial/social support. Male gender of rearing may be a viable option for parents whose children are born with congenital adrenal hyperplasia, a 46,XX karyotype and male genitalia, although positive parental and other support, and counseling are needed for adjustment.

An Evidence-Based Model of Multidisciplinary Care for Patients and Families Affected by Classical Congenital Adrenal Hyperplasia due to 21-Hydroxylase Deficiency

In 2002 a consensus statement pertaining to the management of classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency was jointly produced by the Lawson Wilkins Pediatric Endocrine Society and the European Society of Pediatric Endocrinology. One of the recommendations of this consensus was that centers should maintain multidisciplinary teams for providing care and support to these patients and their families. However, the specifics for how this should be accomplished were not addressed in the original consensus statement. Here we interpret and translate the 2002 consensus statement recommendations into medical, surgical and mental health protocols. Additionally, we provide preliminary evidence that such protocols result in improved care and support for patients and families.

In utero cortisol and testosterone exposure and fear reactivity in infancy

Fetal programming is emerging as a major conceptual model for understanding developmental origins of health and disease, including behavioral outcomes. As part of a larger study of prenatal stress and child development, we examined the association between prenatal hormone exposure and fear reactivity, a temperament dimension that is a predictor of long-term behavioral adjustment. Amniotic fluid was collected from a sample of women undergoing clinically indicated amniocentesis for later analysis of cortisol and testosterone. Children with normal birth outcomes were recalled for follow-up assessment at 17 months, at which time we administered an observational assessment of temperament (lab-TAB; n=108). Information on pregnancy and obstetric outcome was included as covariates. Results indicated that there was a significant association between prenatal testosterone and observed fear reactivity in boys (r(53)=0.34, p=0.01); no significant effect was found in girls (r(54)=-0.07, ns); the effect remained when obstetric, psychosocial, and parental anxiety were controlled for. There was not a significant association between fetal cortisol exposure and fear reactivity. The prediction from in utero testosterone exposure to fear reactivity in boys extends prior research on prenatal testosterone and may represent an association with a general predisposition to greater arousal and reactivity.

Maternal gestational androgen levels in female marmosets (Callithrix geoffroyi) vary across trimesters but do not vary with the sex ratio of litters

Maternal hormones can dramatically modify offspring phenotypes via organizational actions on morphological and behavioral development. In placental mammals, there is the possibility that some portion of hormones in maternal circulation may be derived from fetal origin. We tested the possibility that maternal androgens in pregnant female marmosets reflected, in part, contributions from male fetuses by comparing levels of urinary androgens across pregnancy in females carrying varying numbers of male offspring. We monitored urinary androgen excretion in 18 pregnancies from five female white-faced marmosets (Callithrix geoffroyi). Androgen levels rose significantly in the first trimester of pregnancy, reached a peak in the middle of the second trimester, and then declined gradually until parturition. At no point in pregnancy were levels of urinary androgens higher in females carrying litters that had 50% or more males than in females carrying litters that were less than 50% male. Levels of maternal androgens were not associated with litter size, the number of males in the litter, or with the proportion of the litter that was male. The high levels of androgen in pregnant females are therefore likely of strictly maternal origin, and any modification of fetal growth and development can be considered a 'maternal effect'.

Testosterone, facial symmetry and cooperation in the prisoners' dilemma

Recent research has analyzed how individual characteristics, like the exposure to different hormones and symmetry, affect decision-making and strategic behaviour. The present article investigates the effect of symmetry, of exposure to testosterone (T) in utero and during puberty and of current T on cooperation in a Prisoners' Dilemma Game (PDG). T is a hormone with well known effect on males' behaviour, and that promotes activities that seek to increase reproductive success. Fluctuating Asymmetry (FA) reflects the ability of the organism to maintain a stable development and it is usually employed as a variable reflecting genetic quality (low FA values are thought to signal higher genetic quality). Our results show that subjects with intermediate levels of second to fourth digit ratio (a proxy of exposure to T in utero) and with high FA cooperate more often in the PDG. We also observe that the latter effect is due to the fact that FA has an impact on subjects' expectations about the behaviour of their counterpart in the game. These results reinforce the described link between markers related to genetic quality and cooperative behaviour. This possible linkage of individual condition and pro-social behaviour in humans clearly merits further attention.

Estrogen masculinizes neural pathways and sex-specific behaviors

Sex hormones are essential for neural circuit development and sex-specific behaviors. Male behaviors require both testosterone and estrogen, but it is unclear how the two hormonal pathways intersect. Circulating testosterone activates the androgen receptor (AR) and is also converted into estrogen in the brain via aromatase. We demonstrate extensive sexual dimorphism in the number and projections of aromatase-expressing neurons. The masculinization of these cells is independent of AR but can be induced in females by either testosterone or estrogen, indicating a role for aromatase in sexual differentiation of these neurons. We provide evidence suggesting that aromatase is also important in activating male-specific aggression and urine marking because these behaviors can be elicited by testosterone in males mutant for AR and in females subjected to neonatal estrogen exposure. Our results suggest that aromatization of testosterone into estrogen is important for the development and activation of neural circuits that control male territorial behaviors.

Association study of gender identity disorder and sex hormone-related genes

To investigate the biological mechanism of gender identity disorder (GID), five candidate sex hormone-related genes, encoding androgen receptor (AR), estrogen receptors alpha (ERalpha) and beta (ERbeta), aromatase (CYP19), and progesterone receptor (PGR) were analyzed by a case-control association study. Subjects were 242 transsexuals (74 male-to-female patients (MTF) and 168 female-to-male patients (FTM)), and 275 healthy age- and geographical origin-matched controls (106 males and 169 females). The distributions of CAG repeat numbers in exon 1 of AR, TA repeat numbers in the promoter region of ERalpha, CA repeat numbers in intron 5 of ERbeta, TTTA repeat numbers in intron 4 of CYP19, and six polymorphisms (rs2008112, rs508653, V660L, H770H, rs572698 and PROGINS) of PGR were analyzed. No significant difference in allelic or genotypic distribution of any gene examined was found between MTFs and control males or between FTMs and control females. The present findings do not provide any evidence that genetic variants of sex hormone-related genes confer individual susceptibility to MTF or FTM transsexualism.

Does having a twin brother make for a bigger brain?

OBJECTIVE

Brain volume of boys is larger than that of girls by approximately 10%. Prenatal exposure to testosterone has been suggested in the masculinization of the brain. For example, in litter-bearing mammals intrauterine position increases prenatal testosterone exposure through adjacent male fetuses, resulting in masculinization of brain morphology.

DESIGN

The influence of intrauterine presence of a male co-twin on masculinization of human brain volume was studied in 9-year old twins.

METHODS

Magnetic resonance imaging brain scans, current testosterone, and estradiol levels were acquired from four groups of dizygotic (DZ) twins: boys from same-sex twin-pairs (SSM), boys from opposite-sex twin-pairs (OSM), girls from opposite-sex twin-pairs (OSF), and girls from same-sex twin-pairs (SSF; n=119 individuals). Data on total brain, cerebellum, gray and white matter volumes were examined.

RESULTS

Irrespective of their own sex, children with a male co-twin as compared to children with a female co-twin had larger total brain (+2.5%) and cerebellum (+5.5%) volumes. SSM, purportedly exposed to the highest prenatal testosterone levels, were found to have the largest volumes, followed by OSM, OSF and SSF children. Birth weight partly explained the effect on brain volumes. Current testosterone and estradiol levels did not account for the volumetric brain differences. However, the effects observed in children did not replicate in adult twins.

CONCLUSIONS

Our study indicates that sharing the uterus with a DZ twin brother increases total brain volume in 9-year olds. The effect may be transient and limited to a critical period in childhood.

Androgen receptor in the neural tube of the mouse and chicken embryo

Androgen effects, mediated by the androgen receptor, regulate important cellular processes such as growth, proliferation, and differentiation. The presence of androgen receptor has been described in structures of the central nervous system, mainly in advanced fetuses, newborns, and adult animals. This study describes the presence and location of androgen receptor in early developmental stages of the nervous system. The androgen receptor mRNA was evidenced through reverse transcriptase-PCR and the androgen receptor protein by immunohistochemistry and western blot techniques in the cerebral vesicles of 9.5-day mouse embryos and chicken embryos at stages 8-17 of Hamburger and Hamilton. The androgen receptor protein was located in the nucleus of neuroepithelial cells throughout the neural tube.

Effects of Prenatal Social Stress on Offspring Development

In nonhuman mammals, the social environment in which pregnant females live is critical for their offsprings' brain development, endocrine state, and social and sexual behavior later in life. Social instability during pregnancy generally brings about a behavioral and neuroendocrine masculinization in daughters and a less pronounced expression of male-typical traits in sons. We favor the hypothesis that such behavioral effects of prenatal social stress are not necessarily “pathological” (nonadaptive) consequences of adverse social conditions. Rather, pregnant mothers could be adjusting their offspring to their environment in an adaptive way.

Do women with polycystic ovary syndrome (PCOS) report differences in sex-typed behavior as children and adolescents?: Results of a pilot study

BACKGROUND

The etiology of polycystic ovary syndrome (PCOS) is poorly understood, as is the impact of female hyperandrogenism on psychosocial and psychosexual behavior.

AIM

The present study sought to test whether women with PCOS self-report more masculine sex-typed behavior in childhood, at adolescence, and as adults.

SUBJECTS AND METHODS

Sixty-one women (34 women self-reporting a clinical diagnosis of PCOS and 27 control women not reporting a PCOS diagnosis) completed a questionnaire containing items on childhood sex-typed behavior, adolescent behavior, and present masculinity, femininity and mood.

RESULTS

Results revealed significant differences (p<0.05) in retrospective self-reports of childhood sex-typed behavior and gender conformity according to PCOS status, with women in the PCOS group reporting less feminine childhood behavior, and less gender-typical behavior. A composite of sex-typed behaviors did not differ according to PCOS status at adolescence, although several individual items did. As adults, we found no differences between the groups in masculinity and femininity, although PCOS women reported lower happiness than controls (p<0.05), and trends toward a bisexual orientation and having changed sex orientation more often than controls (p<0.10).

CONCLUSION

Results of this pilot study provide evidence of PCOS women self-reporting discrete psychosocial developmental patterns compared to non-PCOS women. These differences in retrospective self-reported accounts may be factual or biased by current psychosocial differences, such as depression.

Estrogen receptor immunoreactivity in late-gestation fetal lambs

Prenatal androgens masculinize postnatal reproductive neuroendocrine function and behavior in sheep. Testosterone treatment of pregnant ewes during midgestation masculinizes sexual behavior and luteinizing hormone secretion in female lambs, presumably in part via aromatization and estrogen receptor (ESR) binding in the brain. We hypothesized that male and female sheep also differ in the number and distribution of ESR-containing neurons. If so, ESR expression should be sensitive to prenatal hormones delivered exogenously or in situ. ESR alpha (ESR1) was compared by immunocytochemistry in male and female lambs at the end of gestation, as well as in fetal females exposed prenatally to testosterone or dihydrotestosterone. ESR1-positive neurons were abundant in the posteromedial bed nucleus of the stria terminalis (BSTpm), medial preoptic area (MPOA), posterior medial amygdaloid nucleus (MeP), amygdalohippocampal area (AHi), ventromedial hypothalamic nuclei (VMH), and arcuate hypothalamic nuclei (ARC). In females, the ARC had the largest number of stained cells (mean +/- SEM, 475.6 +/- 57.4 cells/0.173 mm(2)), while staining intensity was greatest in the MPOA (mean +/- SEM gray level, 31.3 +/- 5.3). The mean +/- SEM integrated gray level (IGL) was high in the ARC (0.63 +/- 0.13) and in the MPOA (0.51 +/- 0.08). The mean +/- SEM IGL was low in the MeP (0.31 +/- 0.10) and in the BSTpm (0.21 +/- 0.06), while it was intermediate in the AHi (0.36 +/- 0.10) and in the VMH (0.37 +/- 0.07). ESR immunostaining was not significantly different in male and female fetal lambs, nor in females fetuses exposed prenatally to androgens (P > 0.05). However, ESR1 staining was significantly increased in the ARC, MPOA, and AHi of adult rams vs. adult ewes. These results suggest that brain ESR immunoreactivity in fetal lambs is unlikely to account for postnatal sex differences in reproductive function. Instead, sex differences in ESR emerge postnatally.

Differences in Personality Attributions Toward Tattooed and Nontattooed Virtual Human Characters

Individuals with body modifications, such as tattoos, have been shown to differ from nonmodified individuals in sensation-seeking personality characteristics and sociosexuality. This study examined possible differences in people’s attributions of those characteristics toward virtual human characters varying in body modification. Some 287 participants rated tattooed and nontattooed bodies of avatars on aspects of sensation seeking and number of previous sexual partners. Tattooed stimuli were rated as more experience, thrill, and adventure seeking as well as more likely to have a high number of previous sexual partners and as less inhibited when compared to nontattooed stimuli, and this was particularly true for male stimuli. It was concluded that people with body modifications, such as tattoos, are perceived differently compared to nontattooed individuals in terms of sensation seeking and previous sexual partner number, this being particularly true for men. Findings are discussed with reference to the evolutionary model of human sexual selection.

Prenatal exposure to sex steroid hormones and behavioral/cognitive outcomes

Experimental studies in animals indicate that androgen exposure in fetal or neonatal life largely accounts for known sex differences in brain structure and behavior. Clinical research in humans suggests similar influences of early androgen concentrations on some behaviors that show sex differences, including play behavior in childhood and sexual orientation in adulthood. Available research also suggests that sex steroid hormone exposure may contribute to sex differences in the risk of autism and affective disorders in schizophrenia. However, findings have been inconsistent for other characteristics that show sex differences, including aggression and spatial ability. Moreover, social and environmental factors may modulate some of the associations observed. This article reviews the evidence that early-life exposure to sex steroid hormones contributes to sexually dimorphic behavior and cognitive abilities in humans.

Gender assignment and hormonal treatment for disorders of sexual differentiation

PURPOSE

To study the gender assignment and hormonal treatment advocated for disorders of sexual differentiation (DSD).

METHODS

A study was done on patients who were reviewed in the Pediatric Intersex Clinic to evaluate the pattern of gender assignment and hormonal treatment advocated.

RESULTS AND CONCLUSION

The patients included male pseudohermaphrodite (MPH) 169; congenital adrenal hyperplasia (CAH) 91; mixed gonadal dysgenesis (MGD) 29; true hermaphrodite (TH) 25; pure gonadal dysgenesis (PGD) 2; persistent mullerian duct syndrome (PMDS) 2 and others (micropenis, severe hypospadias with cryptorchidism, 46XX male) 39. Out of 91 cases of CAH, 70 (76.9%) were on steroids (prednisolone, hydrocortisone) and/or mineralocorticoids (fluoricortisone) for adrenal suppression. Out of 146 cases of male pseudohermaphrodite and 21 cases of true hermaphrodite and 3 cases of mixed gonadal dysgenesis reared as males, testosterone was given for local application for phallic growth in 101 and/or as systemic injection for mental makeup after puberty in 41 cases. Systemic testosterone injection was also given for 7 cases of CAH reared as males. Out of 26, 15 cases with mixed gonadal dysgenesis and one out of 2 cases of pure gonadal dysgenesis that attained puberty after being reared as females, after female genitoplasty, were given conjugated oestrogen (Premarin) supplemented with progesterone, as the uterus was preserved. For 12 post-pubertal cases of complete androgen insensitivity syndrome (AIS), only premarin was given as there was no uterus. Growth hormone and Gn RH analogue was given in 2 patients with CAH to tide over the early bone maturation induced by hormones with equivocal results. Thus judicious hormonal supplementation based upon type of DSD and gender assigned can provide a psychological and cosmetic benefit to patients with DSD.

Are autistic traits autistic?

According to the extreme male brain theory of autism (Baron-Cohen, 2002), autistic traits would be extreme manifestations of typical male behaviours. The Auyeung et al. (2009) paper establishes a link between autistic traits and higher fetal testosterone (fT) levels in typically developing children. We argue that the construct behind this relationship needs further investigation. First, the link between fT levels and sexually dimorphic traits, that are for example, associated with empathizing and systemizing, is controversial. Likewise, describing autistic behaviours as being extreme male-like is debatable. The cerebral hemisphere laterality pattern of individuals with autism also seems to differ from the pattern typically observed in males. Moreover, the parallel that should exist, according to the fT theory, between individuals with autism and individuals with congenital adrenal hyperplasia (CAH), because of their high fT levels, is unclear. The theory implying fT levels in autism fails to account for a big part of autism, and the link between fT and normal 'autistic traits' hardly demonstrates the causal link between fT and autism.

Fetal testosterone and autistic traits

Studies of amniotic testosterone in humans suggest that fetal testosterone (fT) is related to specific (but not all) sexually dimorphic aspects of cognition and behaviour. It has also been suggested that autism may be an extreme manifestation of some male-typical traits, both in terms of cognition and neuroanatomy. In this paper, we examine the possibility of a link between autistic traits and fT levels measured in amniotic fluid during routine amniocentesis. Two instruments measuring number of autistic traits (the Childhood Autism Spectrum Test (CAST) and the Child Autism Spectrum Quotient (AQ-Child)) were completed by these women about their children (N=235), ages 6-10 years. Intelligence Quotient (IQ) was measured in a subset of these children (N=74). fT levels were positively associated with higher scores on the CAST and AQ-Child. This relationship was seen within sex as well as when the sexes were combined, suggesting this is an effect of fT rather than of sex per se. No relationships were found between overall IQ and the predictor variables, or between IQ and CAST or AQ-Child. These findings are consistent with the hypothesis that prenatal androgen exposure is related to children exhibiting more autistic traits. These results need to be followed up in a much larger sample to test if clinical cases of ASC have elevated fT.

Blocks and bodies: sex differences in a novel version of the Mental Rotations Test

A novel version of the Mental Rotations Test (MRT) that alternated the standard block figures with three-dimensional human figures was administered to 99 men and 129 women. Women and men differed predictably in their retrospective reports of childhood play and digit ratios, a putative measure of prenatal androgen action. Compared to the block figure items, human figure items on the modified MRT were associated with an improvement in performance in both sexes. However, consistent with the study hypothesis, the enhancing effect of the human figure condition on performance as measured by conventional scores was smaller in men compared to women and not at all evident in men when performance was measured by ratio scores. A closer inspection of the human figures effects on test scores showed performance in women improved for both male and female figure items. In contrast, relative to scores on block figure items, performance in men improved when stimuli were male figures but did not improve when stimuli were female figures. These results add to the evidence that the magnitude of sex differences in scores on the MRT may vary according to the test content and item properties. The findings suggest that online measures of cognitive processing in response to different classes of test stimuli (e.g., animate vs. inanimate objects, self-relevant vs. neutral stimuli) may prove useful in research aimed at understanding the hormonal and social factors contributing to the sex difference in performance on the MRT.