Pubertal hormones organize the adolescent brain and behavior

Do Pregnancy-Induced Brain Changes Reverse? The Brain of a Mother Six Years after Parturition

Neuroimaging researchers commonly assume that the brain of a mother is comparable to that of a nulliparous woman. However, pregnancy leads to pronounced gray matter volume reductions in the mother's brain, which have been associated with maternal attachment towards the baby. Beyond two years postpartum, no study has explored whether these brain changes are maintained or instead return to pre-pregnancy levels. The present study tested whether gray matter volume reductions detected in primiparous women are still present six years after parturition. Using data from a unique, prospective neuroimaging study, we compared the gray matter volume of 25 primiparous and 22 nulliparous women across three sessions: before conception (n = 25/22), during the first months of postpartum (n = 25/21), and at six years after parturition (n = 7/5). We found that most of the pregnancy-induced gray matter volume reductions persist six years after parturition (classifying women as having been pregnant or not with 91.67% of total accuracy). We also found that brain changes at six years postpartum are associated with measures of mother-to-infant attachment. These findings open the possibility that pregnancy-induced brain changes are permanent and encourage neuroimaging studies to routinely include pregnancy-related information as a relevant demographic variable.

Effects of ovariectomy on the inputs from the medial nucleus of the amygdala to the ventromedial nucleus of the hypothalamus in young adult rats

During puberty, sexual hormones induce crucial changes in neural circuit organization, leading to significant sexual dimorphism in adult behaviours. The ventrolateral division of the ventromedial nucleus of the hypothalamus (VMHvl) is the major neural site controlling the receptive component of female sexual behaviour, which is dependent on ovarian hormones. The inputs to the VMHvl, originating from the medial nucleus of the amygdala (MeA), transmit essential information to trigger such behaviour. In this study, we investigated the projection pattern of the MeA to the VMHvl in ovariectomized rats at early puberty. Six-week-old Sprague-Dawley rats were ovariectomized (OVX) and, upon reaching 90 days of age, were subjected to iontophoretic injections of the neuronal anterograde tracer Phaseolus vulgaris leucoagglutinin into the MeA. Projections from the MeA to the VMHvl and to other structures included in the neural circuit responsible for female sexual behaviour were analysed in the Control and OVX groups. The results of the semi-quantitative analysis showed that peripubertal ovariectomy reduced the density of intra-amygdalar fibres. The stereological estimates, however, failed to find changes in the organization of the terminal fields of nerve fibres from the MeA to the VMHvl in the adult. The present data show that ovariectomized rats during the peripubertal phase did not undergo significant changes in MeA fibres reaching the VMHvl; however, they suggest a possible effect of ovariectomy on MeA connectivity under amygdalar subnuclei.

Posttraumatic Stress Disorder and the Developing Adolescent Brain

Posttraumatic stress disorder (PTSD) in adolescents is common and debilitating. In contrast to adult PTSD, relatively little is known about the neurobiology of adolescent PTSD, nor about how current treatments may alter adolescent neurodevelopment to allow recovery from PTSD. Improving our understanding of biological mechanisms of adolescent PTSD, taken in the context of neurodevelopment, is crucial for developing novel and personalized treatment approaches. In this review, we highlight prevailing constructs of PTSD and current findings on these domains in adolescent PTSD. Notably, little data exist in adolescent PTSD for prominent adult PTSD constructs, including threat learning and attentional threat bias. Most work to date has examined general threat processing, emotion regulation, and their neural substrates. These studies suggest that adolescent PTSD, while phenomenologically similar to adult PTSD, shows unique neurodevelopmental substrates that may impair recovery but could also be targeted in the context of adolescent neuroplasticity to improve outcomes. Both cross-sectional and longitudinal data suggest abnormal frontolimbic development compared with typically developing youths, a pattern that may differ from resilient youths. Whether current treatments such as trauma-focused psychotherapy engage these targets and restore healthy neurodevelopment remains an open question. We end our review by highlighting emerging areas and knowledge gaps that could be addressed to better characterize the biology underlying adolescent PTSD. Emerging studies in computational modeling of decision making, caregiver-related transmission of traumatic stress, and other areas may offer new targets that could harness adolescent neurobehavioral plasticity to improve resilience and recovery for some of our most vulnerable youths.

Kisspeptin and neurokinin B expression in the human hypothalamus: Relation to reproduction and gender identity

Gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus are at the core of reproductive functioning. GnRH released into the median eminence regulates the secretion of the gonadotropins from the anterior pituitary, which in turn activates gametogenesis and steroid synthesis by the gonads. The GnRH system displays functional sex differences: GnRH is secreted in pulses at a constant frequency in men, whereas in women, pulse frequency varies over the menstrual cycle. In both sexes, GnRH release is regulated by sex steroid hormones, acting at the level of the hypothalamus and the anterior pituitary in a classic feedback loop. Because GnRH neurons do not express sex steroid receptors, hormone effects on GnRH release are presumed to be mediated indirectly through other steroid-sensitive neuronal systems, which then converge onto GnRH cell bodies and/or terminals. Human genetic studies demonstrated that kisspeptin (KP) as well as neurokinin B (NKB) signaling are both potent regulators of GNRH secretion. In humans, postmortem studies using immunohistochemistry have shown that women have higher KP and NKB expression in the infundibular nucleus than men. Sex differences in KP expression are present throughout life, which is from the infant/prepubertal into the elderly period, whereas sex differences in NKB expression do not emerge until adulthood. KP and NKB are often coexpressed together with dynorphin by the same population of neurons, also known as KDNy neurons in other species. Indeed, significant coexpression between KP and NKB but not with Dynorphin has been observed thereby challenging the KDNy concept in humans. Female-typical expression of both KP and NKB were observed in the infundibular nucleus of trans women (male sex assigned at birth and female gender identity). Taken together, sex differences in KP and NKB expression most likely reflect organizational actions of sex steroid hormones on the developing brain but they also remain sensitive to circulating sex steroids in adulthood. The female-dominant sex difference in infundibular KP and NKB expression suggests that this brain region is most likely involved in both the negative and positive feedback actions of estrogens on GnRH secretion. Finally, the sex-reversal observed in KP and NKB expression in trans women might reflect, at least partially, an atypical sexual differentiation of the brain.

Pornography Use Could Lead to Addiction and Was Associated With Reproductive Hormone Levels and Semen Quality: A Report From the MARHCS Study in China

This study aimed to investigate the situations of pornography use among male college students of China, to explore the addiction possibility for pornography use, and to study the associations between pornography use and reproductive hormone levels and semen quality. Five hundred sixty-eight participants met the inclusion criteria and finished all of the questionnaires and hormone level and semen parameter examinations. A majority of participants (except one) had pornography use experience, 94.2% participants started pornography use before college, and 95.9% participants reported they had masturbation experience when using pornography. Early contact to pornography, frequent pornography use, high amount of time spending on pornography use, and frequent masturbation during pornography use were correlated with addiction trends. Earlier pornography use was found to be associated with lower serum prolactin (PRL), follicle-stimulating hormone (FSH), and progesterone (Prog), as well as lower sperm concentration and total sperm count. Higher frequency of pornography use was associated with lower serum estrogen (E₂). In conclusion, pornography use was common among male college students in China. Early contact, high frequent use, and high frequency of masturbation during pornography use could lead to addiction trends and aberrant reproductive hormone levels and semen quality.

Shaping of the Female Human Brain by Sex Hormones: A Review

Traditionally sex hormones have been associated with reproductive and developmental processes only. Since the 1950s we know that hormones can have organizational effects on the developing brain and initiate hormonal transition periods such as puberty. However, recent evidence shows that sex hormones additionally structure the brain during important hormonal transition periods across a woman's life including short-term fluctuations during the menstrual cycle. However, a comprehensive review focusing on structural changes during all hormonal transition phases of women is still missing. Therefore, in this review structural changes across hormonal transition periods (i.e., puberty, menstrual cycle, oral contraceptive intake, pregnancy and menopause) were investigated in a structured way and correlations with sex hormones evaluated. Results show an overall reduction in grey matter and region-specific decreases in prefrontal, parietal and middle temporal areas during puberty. Across the menstrual cycle grey matter plasticity in the hippocampus, the amygdala as well as temporal and parietal regions were most consistently reported. Studies reporting on pre- and post-pregnancy measurements revealed volume reductions in midline structures as well as prefrontal and temporal cortices. During perimenopause, the decline in sex hormones was paralleled with a reduction in hippocampal and parietal cortex volume. Brain volume changes were significantly correlated with estradiol, testosterone and progesterone levels in some studies, but directionality remains inconclusive between studies. These results indicate that sex hormones play an important role in shaping women's brain structure during different transition periods and are not restricted to specific developmental periods.

Social position in a peer group of school-aged boys and selected biological parameters

The period of adolescence includes biological, psychological and social maturation. All these processes complement and affect each other. The ultimate goal is the transition from childhood to adulthood which enables individuals to become socialized beings, who are psychologically mature and able to pass on their genetic inheritance. In the process of reaching full maturity, adolescents are exposed to both positive and negative stimuli the socio-cultural environment. In the process of socialization, the influence of peers, and the maturing into social roles is important. At the same time, adolescents mature biologically. A holistic understanding of the sequence of changes that occur during adolescence foregrounds the significance of biology in informing emotions and cognition. Research conducted on adolescents from Wrocław, Poland, showed the impact that physical development plays on social development within a school peer group. Adolescents with a slower pace of maturity, lower BMI, and lower body height achieved the lowest social status in the group’s hierarchy. These adolescents also became victims of peer rejection. The role of scapegoat assigned to them highlighted and completed the symptomatic rejection process, which highlighted negative social group behaviours. In contrast, their peers from the same classes, with higher biological parameters, became leaders in the school’s social groups. Furthermore, sociometric ‘stars’, leaders and gray eminences, compared to scapegoats, achieved maturity faster, and had greater body height and higher BMI among all age groups.

Myelin development in cerebral gray and white matter during adolescence and late childhood

Myelin development during adolescence is becoming an area of growing interest in view of its potential relationship to cognition, behavior, and learning. While recent investigations suggest that both white matter (WM) and gray matter (GM) undergo protracted myelination during adolescence, quantitative relations between myelin development in WM and GM have not been previously studied. We quantitatively characterized the dependence of cortical GM, WM, and subcortical myelin density across the brain on age, gender, and puberty status during adolescence with the use of a novel macromolecular proton fraction (MPF) mapping method. Whole-brain MPF maps from a cross-sectional sample of 146 adolescents (age range 9–17 years) were collected. Myelin density was calculated from MPF values in GM and WM of all brain lobes, as well as in subcortical structures. In general, myelination of cortical GM was widespread and more significantly correlated with age than that of WM. Myelination of GM in the parietal lobe was found to have a significantly stronger age dependence than that of GM in the frontal, occipital, temporal and insular lobes. Myelination of WM in the temporal lobe had the strongest association with age as compared to WM in other lobes. Myelin density was found to be higher in males as compared to females when averaged across all cortical lobes, as well as in a bilateral subcortical region. Puberty stage was significantly correlated with myelin density in several cortical areas and in the subcortical GM. These findings point to significant differences in the trajectories of myelination of GM and WM across brain regions and suggest that cortical GM myelination plays a dominant role during adolescent development.

A person-centered examination of emotion dysregulation, sensitivity to threat, and impulsivity among children and adolescents: An ERP study

Objectives

Adolescence often is characterized by the onset of social anxiety and risk taking; yet, not all youth are anxious and/or risk takers. There are several factors that may help differentiate youth with anxiety (e.g., threat sensitivity and emotion dysregulation) and youth who take risks (e.g., impulsivity and emotion dysregulation). We conducted a latent class analysis to identify groups of youth who differ in these processes, and then investigated group differences on the error-related negativity, an ERP that has been differentially associated with threat sensitivity and impulsivity.

Method

Youth (N = 1313, M_age = 11, range = 8–15 years) completed a survey assessing their emotion dysregulation, sensitivity to threat, and impulsivity. A subsample (N = 424) also completed a go/no-go task while EEG was recorded.

Results and conclusions

Four groups were identified with differential levels of emotion dysregulation, sensitivity to threat, and impulsivity. Adolescents had greater odds than children of being in the High_Dysregulation/ThreatSensitivity or ModerateDysregulation/HighImpulsivity Groups in comparison to two other groups with lower scores. The High_Dysregulation/ThreatSensitivity Group had the largest ERN, while the ModerateDysregulation/HighImpulsivity Group had the smallest ERN. The ERN may be a potential biomarker to help distinguish between different profiles of adolescents who may be at risk for either anxiety or risk taking.

The effects of early life stress on motivated behaviors: A role for gonadal hormones

Motivated behaviors are controlled by the mesocorticolimbic dopamine (DA) system, consisting of projections from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) and prefrontal cortex (PFC), with input from structures including the medial preoptic area (mPOA). Sex differences are present in this circuit, and gonadal hormones (e.g., estradiol and testosterone) are important for regulating DA transmission. Early life stress (ELS) also regulates the mesocorticolimbic DA system. ELS modifies motivated behaviors and the underlying DA circuitry, increasing risk for disorders such as substance use disorder, major depression, and schizophrenia. ELS has been shown to change gonadal hormone signaling in both sexes. Thus, one way that ELS could impact mesocorticolimbic DA is by altering the efficacy of gonadal hormones. This review provides evidence for this idea by integrating the gonadal hormone, motivation, and ELS literature to argue that ELS alters gonadal hormone signaling to impact motivated behavior. We also discuss the importance of these effects in the context of understanding risk and treatments for psychiatric disorders in men and women.

Pubertal Timing During Early Adolescence: Advanced Pubertal Onset in Females with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is characterized by impaired social communication and poor adaptation to change; thus, the onset of puberty may be a pivotal transition. This cross-sectional study measured pubertal timing to examine hypothesized differences for sex (female vs. male) and group (ASD vs. typical development [TD]). Participants included 239 children (137 ASD, 102 TD) between 10 and 13 years. The ASD group included 35 females and 102 males; the TDs included 44 females and 58 males. Pubertal onset measured by genital or pubic stage was investigated with linear regression using main effects of sex and age-by-sex interactions in TD and ASD groups and main effects of diagnosis and diagnosis-by-age interactions in males and females, controlling for body mass index, socioeconomic status, and race. In TD, examination of main effects for genital (penis/breast) stage showed no difference for male and female children (t = 1.33, P = 0.187, rdf = 92); however, there were significant differences in ASD (t = 2.70, P = 0.008, rdf = 121). For diagnosis modeled separately by sex, there was significantly earlier pubertal development in females with ASD (t = 1.97, P = 0.053, rdf = 70, but not males (t = 1.329, P = 0.186, rdf = 143). In addition, analysis of menses revealed females with ASD had significantly earlier onset than TD (t = -2.56, P = 0.018, rdf = 21). Examination of pubic stage revealed expected sex differences for TD (t = 2,674, P = 0.009, rdf = 91) and ASD (t = 3.482, P = 0.001, rdf = 121). Females with ASD evidence advanced pubertal onset relative to ASD males and TD females. Findings underscore the need for enhanced understanding of pubertal development in ASD, as differences may have significant psychological, social, physiological, and developmental consequences. LAY SUMMARY: Children with autism spectrum disorder (ASD) have difficulty with social communication and respond poorly to change, which may include the onset and course of puberty. The study measured the timing of puberty in 239 children (137 ASD and 102 typical development [TD]) between 10 and 13 years based on pubertal stage of genital (breast/penis) and pubic hair development. Females with ASD evidence advanced pubertal onset relative to ASD males and TD females. Findings underscore the need for an enhanced understanding of pubertal development in ASD.

HPG-Dependent Peri-Pubertal Regulation of Adult Neurogenesis in Mice

Adult neurogenesis, a striking form of neural plasticity, is involved in the modulation of social stimuli driving reproduction. Previous studies on adult neurogenesis have shown that this process is significantly modulated around puberty in female mice. Puberty is a critical developmental period triggered by increased secretion of the gonadotropin releasing hormone (GnRH), which controls the activity of the hypothalamic-pituitary-gonadal axis (HPG). Secretion of HPG-axis factors at puberty participates to the refinement of neural circuits that govern reproduction. Here, by exploiting a transgenic GnRH deficient mouse model, that progressively loses GnRH expression during postnatal development (GnRH::Cre;Dicer ^loxP/loxP mice), we found that a postnatally-acquired dysfunction in the GnRH system affects adult neurogenesis selectively in the subventricular-zone neurogenic niche in a sexually dimorphic way. Moreover, by examining adult females ovariectomized before the onset of puberty, we provide important evidence that, among the HPG-axis secreting factors, the circulating levels of gonadal hormones during pre-/peri-pubertal life contribute to set-up the proper adult subventricular zone-olfactory bulb neurogenic system.

Postweaning Grouping as a Strategy to Reduce Singly Housed Male Mice

Simple Summary

It is important to raise laboratory mice in stable groups. However, sometimes we can find litters with only one male. Unfortunately, age is a factor to consider when grouping a newly weaned mouse with other males due to inter-male aggressiveness. Our results showed that CD1 and SCID Beige newly weaned males can be safely grouped with juvenile and pubescent mice. However, only juvenile C57BL/6J will accept a newly weaned mouse as a new member of the group. This strategy could be helpful to reduce the number of singly housed male mice used for scientific purposes.

Abstract

Rearing laboratory mice in groups is important since social isolation after weaning induces brain alterations, which entails behavioral abnormalities in adulthood. Age is an important factor when grouping males of different litters due to inter-male aggressiveness. The aim of this study was to determine whether newly weaned mice could safely be grouped with late juvenile or early and late pubescent mice, and whether cage cleaning, the number of the hosting group members and testosterone plasma levels have any influence. Newly weaned C57BL/6J, CD1, and SCID Beige male mice were systematically grouped with same strain late juvenile, early or late pubescent male mice in clean or dirty cages of 1, 2 or 3 hosting members. We also analyzed plasma testosterone levels at different postnatal days. Our result showed that only strain and hosting male’s age influence agonistic behavior toward newly weaned mice. Thus, in order not to house a recently weaned male alone, we would recommend grouping it with late juvenile same strain mice in all studied strains. In the same way, CD1 and SCID Beige pubescent mice will admit a newly weaned mouse in their group. However, we would not recommend grouping newly weaned and pubescent C57BL/6J males.

Sex continuum in the brain and body during adolescence and psychological traits

Many traits of the brain and body show marked sex differences, but the distributions of their values overlap substantially between the two sexes. To investigate variations associated with biological sex, beyond binary differences, we create continuous sex scores capturing the inter-individual variability in phenotypes. In an adolescent cohort (n = 1,029; 533 females), we have generated three sex scores based on brain-body traits: 'overall' (48 traits), 'pubertal' (26 traits) and 'non-pubertal' (22 traits). We then conducted sex-stratified multiple linear regressions (adjusting for age) using sex scores to test associations with sex hormones, personality traits and internalizing-externalizing behaviour. Higher sex scores (that is, greater 'femaleness') were associated with lower testosterone in males only, as well as lower extraversion, higher internalizing and lower externalizing in both sexes. The associations with testosterone, internalizing and externalizing were driven by pubertal sex scores, underscoring the importance of adolescence in shaping within-sex individual variability.

Harms associated with inhalant misuse in adolescent females - a review of the pre-clinical and clinical evidence

BACKGROUND

Inhalant misuse, or the misuse of products containing toluene is common in adolescents, and is associated with diverse physiological and psychological harms. Females comprise over half those who misuse inhalants in adolescence, however, the majority of the evidence has been derived from male-only or mixed-sex studies without exploration of sex differences. Female adolescence is a critical maturational period with potential for growth, reproductive, cognitive and psychological harms that may lead to long-term health consequences. We therefore summarise evidence of female-specific harms arising from inhalant misuse.

METHODS

We synthesised pre-clinical and clinical studies of inhalant misuse which were conducted in females, or where sex-differences were reported, into a narrative literature review.

RESULTS

Females experience growth impairments and metabolic dysfunction arising from inhalant misuse, but data on sex-differences are inconclusive. Inhalant misuse in early adolescence may impact menarche and subsequent reproductive capacity, but studies have predominantly focused on the effects of inhalants on offspring rather than on the exposed female. There is limited evidence of sex-differences in relation to cognitive outcomes following exposure to inhalants in pre-clinical models. Females are at an increased risk of psychological harms associated with inhalant misuse, particularly depression and suicidal behaviour.

CONCLUSIONS

The type and magnitude of harms associated with inhalant misuse are sex-specific, but data are limited. We recommend that both pre-clinical and clinical studies of inhalant misuse include both males and females, and should specifically test for and report sex-differences. This can be used to build an evidence base for screening and interventions tailored to females.

Sex and age differences in locomotor and anxiety-like behaviors in rats: From adolescence to adulthood

Risk-taking behaviors are a primary contributor to elevated adolescent injury and mortality. Locomotor and anxiety-like behaviors in rodents have been used to examine risk-taking. Here, we examined risk-taking behavior (i.e., changes in locomotor and anxiety-like behaviors) from early to late adolescence and adulthood in male and female rats in the open-field (OF) apparatus and the light-dark (LD) test. We also examined whether these behaviors are affected by an early adolescent immune stressor, lipopolysaccharide (LPS). Long-Evans male and female rats were injected with LPS (200 μg/kg) or vehicle control in early adolescence (postnatal day [PND] 30 and 32). Anxiety-like behavior and locomotor activity were measured in early (PND 38-40), late adolescence (PND 50), and adulthood (PND 88 and 98) in the OF and in early adolescence (PND 42) and adulthood (PND 90) in the LD test. Early and late adolescent rats displayed significantly greater locomotor and anxiety-like behaviors than adult rats in the OF and LD test. Sex differences were also found, with adolescent and adult females displaying greater locomotor and anxiety-like behaviors than male rats in the OF and LD tests. LPS administered two times in early adolescence did not have a significant impact on either locomotor or anxiety-like behaviors suggesting minimal impact of the immune stressor.

Trajectories of Adolescents Treated with Gonadotropin-Releasing Hormone Analogues for Gender Dysphoria

Gonadotropin-releasing hormone analogues (GnRHa) are recommended as initial treatment for adolescents diagnosed with gender dysphoria, providing time to follow gender identity development and consider further treatment wishes without distress caused by unwanted pubertal changes. This has been described as an extended diagnostic phase. However, there are also concerns about the physical, neurocognitive, and psychosocial effects of this treatment. In this retrospective study, we document trajectories after the initiation of GnRHa and explore reasons for extended use and discontinuation of GnRHa. Treatment was considered appropriate in 143 (67%) of the 214 adolescents eligible for GnRHa treatment by virtue of their age/pubertal status, and all started GnRHa (38 transgirls, 105 transboys; median age, 15.0 years [range, 11.1-18.6] and 16.1 years [range, 10.1-17.9]). After a median duration of 0.8 years (0.3-3.8) on GnRHa, 125 (87%) started gender-affirming hormones (GAH). Nine (6%) discontinued GnRHa, five of whom no longer wished gender-affirming treatment. Thirteen had used GnRHa for longer than required by protocol for reasons other than logistics and regularly met with a mental health professional during this time, supporting the use of GnRHa treatment as an extended diagnostic phase. In conclusion, the vast majority who started GnRHa proceeded to GAH, possibly due to eligibility criteria that select those highly likely to pursue further gender-affirming treatment. Due to the observational character of the study, it is not possible to say if GnRHa treatment itself influenced the outcome. Few individuals discontinued GnRHa, and only 3.5% no longer wished gender-affirming treatment.

Sex differences of inflammatory and immune response in pups of Wistar rats with SIRS

It is a common fact, that the content of sex hormones in humans and animals varies in different age periods. The functional state of the immune system also changes with age. However, sex differences studies of inflammatory and immune responses during puberty prevail in literature. Investigation of immune responses to LPS peculiarities in prepubertal females and males may contribute to the development of more effective immunotherapy and minimize side effects of children vaccination. Therefore, the aim of this work was to investigate the LPS-induced SIRS sex differences in prepubertal Wistar rats. Despite the absence of sex differences in estradiol and testosterone levels, LPS-induced inflammatory changes in liver and lungs are more pronounced among males. Males demonstrate the increasing neopterin, corticosterone levels and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Not less important is that in females, demonstrating less morphological changes in liver and lungs, endotoxin level is tenfold higher, and corticosterone level decreases. Thus, endotoxin cannot be used as a marker of the severity of multiple organ failure in prepubertal period. The LPS-induced immune reactions in females and males are similar and are characterized by immunosuppression. Both females and males have decreased production of cytokines (IL-2, IL-4, TNF-α, TGF-β) and the absolute number of CD3 + and CD3 + CD8 + lymphocytes in blood. The acute atrophy of thymus and apoptosis of thymic cells are revealed in animals of both sexes. However, the number of CD3 + CD4 + T-helpers and CD4 + CD25 + Foxp3 + T-cells decreases only in females with SIRS, and in males there was a decrease of CD45R + B-cells. The least expressed sex differences in immune responses in the prepubertal period can be determined by the low levels of sex steroids and the absence of their immunomodulatory effect. Further studies require the identification of mechanisms, determining the sex differences in the inflammatory and immune responses in prepubertal animals.

Big five personality traits and common mental disorders within a hierarchical taxonomy of psychopathology: A longitudinal study of Mexican-origin youth

The present study (a) tested whether a structure of common mental disorders within the hierarchical taxonomy of psychopathology was invariant from late childhood to adolescence in a sample of Mexican-origin youth, (b) examined the developmental course of psychopathology at different levels of the hierarchy, and (c) tested the degree to which changes in psychopathology were associated with changes in the Big Five personality domains. Results were consistent with the longitudinal hierarchical invariance of common mental disorders from age 12 to 17 (n = 674). Further, initial levels of conscientiousness, agreeableness, and emotional stability were positively associated with lower initial levels of a higher order factor of psychopathology, and increases in extraversion and decreases in neuroticism were associated with decreases in a higher order factor of psychopathology, which captured the general tendency for externalizing, internalizing, and attention-hyperactivity-related dimensions of psychopathology to correlate. Results of the present study indicate that a hierarchical model of common mental disorders extends to Mexican-origin youth and that developmental change in Big Five personality are related to developmental change in psychopathology. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Perinatal androgens organize sex differences in mast cells and attenuate anaphylaxis severity into adulthood

Mast cell (MC)-associated diseases, including allergy/anaphylaxis and neuroinflammatory pain disorders, exhibit a sex bias, with females at increase risk. While much attention has been directed toward adult sex hormones as drivers of sex differences, that female sex bias in MC-associated diseases is evident in prepubertal children, suggesting early-life origins of sex differences which have yet to be explored. Utilizing rodent models of MC-mediated anaphylaxis, our data here reveal that, 1) compared with females, males exhibit significantly reduced severity of MC-mediated anaphylactic responses that emerge prior to puberty and persist into adulthood, 2) reduced severity of MC-mediated anaphylaxis in males is linked with the naturally high level of perinatal androgens and can be recapitulated in females by perinatal exposure to testosterone proprionate, 3) perinatal androgen exposure guides bone marrow MC progenitors toward a masculinized tissue MC phenotype characterized by decreased concentration of prestored MC granule mediators (e.g., histamine, serotonin, and proteases) and reduced mediator release upon degranulation, and 4) engraftment of MC-deficient Kit W-sh/W-sh mice with adult male, female, or perinatally androgenized female MCs results in MC-mediated anaphylaxis response that reflects the MC sex and not host sex. Together, these data present evidence that sex differences in MC phenotype and resulting disease severity are established in early life by perinatal androgens. Thus, factors affecting levels of perinatal androgens could have a significant impact on MC development and MC-associated disease risk across the life span.

Pubertal timing predicts adult psychosexuality: Evidence from typically developing adults and adults with isolated GnRH deficiency

Evidence suggests that psychosexuality in humans is modulated by both organizational effects of prenatal and peripubertal sex steroid hormones, and by activational effects of circulating hormones in adulthood. Experimental work in male rodents indicates that sensitivity to androgen-driven organization of sexual motivation decreases across the pubertal window, such that earlier puberty leads to greater sex-typicality. We test this hypothesis in typically developing men (n = 231) and women (n = 648), and in men (n = 72) and women (n = 32) with isolated GnRH deficiency (IGD), in whom the precise timing of peripubertal hormone exposure can be ascertained via the age at which hormone replacement therapy (HRT) was initiated. Psychosexuality was measured with the Sexual Desire Inventory-2 (SDI-2) and Sociosexual Orientation Inventory-Revised (SOI-R). In both sexes, earlier recalled absolute pubertal timing predicted higher psychosexuality in adulthood, although the magnitude of these associations varied with psychosexuality type and group (i.e., typically developing and IGD). Results were robust when controlling for circulating steroid hormones in typically developing participants. Age of initiation of HRT in men with IGD negatively predicted SOI-R. We discuss the clinical implications of our findings for conditions in which pubertal timing is medically altered.

Increased dehydroepiandrosterone (DHEA) is associated with anxiety in adolescent girls

The pubertal period is a time of rapid increase in the incidence of anxiety disorders, and thus, pubertal hormones may play a role in the precipitation of anxious psychopathology. DHEA, a steroid hormone that surges in adolescence, has been previously linked to anxiety, although the direction of this effect has been mixed. Using a cross-sectional design in a sample of 286 adolescent girls, the present study examined associations between salivary DHEA concentrations and self-report and interview-based measures of anxiety while controlling for pubertal status, menarche status, assessment time of day, and other hormones including testosterone, estradiol, and progesterone. Increased salivary DHEA concentrations were associated with more self-reported anxiety symptoms, increased anxiety symptom counts based on clinical interview, and increased probability of an anxiety disorder. Out of all anxiety symptom domains examined, generalized anxiety disorder symptoms were the best predictor of salivary DHEA concentrations after controlling for pubertal development. Collectively, our findings suggest relevance for DHEA in the development of anxiety in the pubertal period, as well as a robust relationship between DHEA and emerging symptoms of pathological worry during adolescence. The present study underscores the importance of examining associations between DHEA concentrations and anxiety in longitudinal designs.

Sexual Differentiation and Substance Use: A Mini-Review

The organizational/activational hypothesis suggests that gonadal steroid hormones like testosterone (T) and estradiol (E2) are important at 2 different times during the lifespan when they perform 2 different functions. First steroids "organize" brain structures early in life and during puberty, and in adults these same hormones "activate" sexually dimorphic behaviors. This hypothesis has been tested and proven valid for a large number of behaviors (learning, memory, social, and sexual behaviors). Sex differences in drug addiction are well established both for humans and animal models. Previous research in this field has focused primarily on cocaine self-administration by rats. Traditionally, observed sex differences have been explained by the sex-specific concentrations of gonadal hormones present at the time of the drug-related behavior. Studies with gonadectomized rodents establishes an activational role for E2 that facilitates vulnerability in females, and when E2 is combined with progesterone, addiction is attenuated. Literature on organizational actions of steroids is sparse but predicts that T, after it is aromatized to E2, changes aspects of the neural reward system. Here we summarize these data and propose that sex chromosome complement also plays a role in determining sex-specific drug-taking behavior. Future research is needed to disentangle the effects of hormones and sex chromosome complement, and we propose the four core genotype mouse model as an effective tool for answering these questions.

Domain- and trimester-specific effect of prenatal phthalate exposure on preschooler cognitive development in the Ma'anshan Birth Cohort (MABC) study

BACKGROUND

Phthalates are a group of heavily produced endocrine disruptors that are widely used in personal care products, food packaging, building materials, and medical device. Few epidemiological studies have examined the effect of repeated prenatal exposure to multiple phthalates on preschooler cognitive development.

OBJECTIVES

This study aimed to examine the association between prenatal phthalate exposure measured at multiple time points and the intelligent quotient (IQ) scores of preschoolers, and to further identify the critical windows and specific intelligence domains in which phthalate exposure would affect preschooler cognitive development.

METHODS

The current study was based on the Ma'anshan Birth Cohort (MABC) study. Seven phthalate metabolites were measured in 2128 maternal urine samples collected during the first, second, and third trimesters of pregnancy. The IQ score of preschool-aged children were assessed with the Chinese version of the Wechsler Preschool and Primary Scale of Intelligence, Fourth edition (WPPSI-Ⅳ CN). Linear mixed models (LMMs) were used to assess the longitudinal effects of repeated prenatal phthalate exposure on children's IQ score. Multiple linear regression models were fitted to determine whether critical window phthalate exposure would affect cognitive development of children.

RESULTS

Overall, the repeated measures analysis indicated that the verbal comprehension index (VCI), visual space index (VSI) and full-scale intelligence quotient (FSIQ) decreased by 0.30 (95% CI: -0.60, 0; p = 0.05), 0.32 (95% CI: -0.62, -0.01; p = 0.04), and 0.31 (95% CI:-0.57, -0.04; p = 0.02) points, respectively, with each ln-transformed increase in the metabolite concentration of MBP. The fluid reasoning index (FRI) and processing speed index (PSI) increased by 0.30 (95% CI: 0.07, 0.54; p = 0.01) and 0.28 (95% CI: 0.06, 0.51; p = 0.01) points, respectively, with each ln-concentration increase in MEP. Trimester-specific regression models stratified by the sample collection time during pregnancy generated consistent results. In the first trimester, each ln-transformed MBP increase was associated with reductions in VCI, VSI and FSIQ of 0.56 (95% CI:-1.09, -0.02; p = 0.04), 0.60 (95% CI:-1.15, -0.05; p = 0.03) and 0.49 (95% CI:-0.97, -0.01; p = 0.04) points, respectively. In the third trimester, we observed that only MBzP exposure was associated with an increase in VCI (β: 0.48, 95% CI: 0.03, 0.92; p = 0.04). The gender-stratified analyses revealed that boys drove these associations.

CONCLUSIONS

Our results suggest that prenatal phthalate exposure impairs the cognitive development of preschoolers. The first trimester of pregnancy might be the most vulnerable period in terms of neurotoxicitydue to phthalate exposure. These findings warrant further confirmation.

The Disruptive Effects of Estrogen Removal before Puberty on Risk for Binge Eating in Female Rats

Recent research suggests that estrogen is protective against binge eating in adult females, and that pubertal estrogen may be critical for these effects. Nonetheless, to date, no study has examined the role of pubertal estrogen in adult binge eating phenotypes in females, potentially due to difficulties experimentally manipulating estrogen in humans to examine causal effects. We used a novel animal model to examine whether estrogen removal prior to puberty (via pre-pubertal ovariectomy (P-OVX)) increases rates of binge eating prone (BEP) phenotypes in adulthood in females. A total of 77 P-OVX and 79 intact rats were followed from pre-puberty into adulthood and phenotyped for BEP status in adulthood. Results showed significantly increased rates (~2-8x higher) of adult BEP phenotypes in P-OVX as compared to intact rats. Findings confirm that estrogen removal substantially increases later risk for binge eating in females, potentially by disrupting typical adolescent brain development.

Pubertal recalibration of cortisol-DHEA coupling in previously-institutionalized children

As a period of heightened plasticity, puberty may provide a window of opportunity for recalibration of the hypothalamic-pituitary-adrenal (HPA) axis to current conditions. Our group has recently documented evidence for pubertal recalibration of HPA axis reactivity among children internationally adopted as infants from institutions into supportive, well-resourced homes. As a first step at examining potential mechanisms by which puberty may facilitate recalibration of the HPA axis, the current study assessed whether previously-institutionalized (PI) children differed from non-adopted (NA) comparison children in levels of the adrenal steroid hormone dehydroepiandrosterone (DHEA) and in its intra-individual covariation (coupling) with cortisol by adrenal pubertal stage. In an accelerated longitudinal design, 7- to 15-year-olds completed up to 3 annual assessments, which included nurse-conducted pubertal staging and the Modified Trier Social Stress Test for Children (TSST-M). Adrenal (pubic hair) rather than gonadal pubertal stage scores were used in the analysis. Paired salivary cortisol-DHEA samples were available at 60-80 min post-TSST-M. NA and PI children did not differ in DHEA levels, which were higher among children at more advanced pubertal stages (averaged across the sessions) for both groups. For NA children, post-stressor cortisol and DHEA were positively coupled across sessions at all average adrenal pubertal stages. For PI children who were, on average, at earlier adrenal pubertal stages, post-stressor cortisol and DHEA were not coupled, but PI children who were at later pubertal stages demonstrated positive cortisol-DHEA coupling similar to that of the NA children. We suggest that these findings provide insights into processes which may underlie pubertal recalibration of the HPA axis.

Suppression of ovarian hormones in adolescent rats has no effect on anxiety-like behaviour or c-fos activation in the amygdala

In humans, sex differences in mood disorders emerge during adolescence, with prevalence rates being consistently higher in females than males. It has been hypothesised that exposure to endogenous ovarian hormones during adolescence enhances the susceptibility of females to mood disorders from this stage of life onwards. However, experimental evidence in favour of this hypothesis is lacking. In the present study, we examined the long-term effects of suppressing adolescent gonadal hormone levels in a group of female Lister-hooded rats via administration of a gonadotrophin-releasing hormone antagonist (Antide; administered on postnatal day [PND] 28 and 42) compared to control females and males (n = 14 per group). We predicted that, in adulthood, Antide-treated female rats would exhibit more male-like behaviour than control females in novel environments (elevated-plus maze, open field and light-dark box), in response to novel objects and novel social partners, and in an acoustic startle task. Progesterone and luteinising hormone assays (which were conducted on blood samples collected on PND 55/56 and 69/70) confirmed that the hypothalamic-pituitary-gonadal axis was temporarily suppressed by Antide treatment. In addition, Antide-treated females were found to exhibit a modest pubertal delay, as measured by vaginal opening, which was comparable in length to the pubertal delay that has been induced by adolescent exposure to alcohol or stress in previous studies of female rats. However, Antide-treated females did not substantially differ from control females on any of the behavioural tests, despite the evidence for predicted sex differences in some measures. Following the acoustic startle response task, all subjects were culled and perfused, and c-Fos staining was conducted in the medial and basolateral amygdala, with the results showing no significant differences in cell counts between the groups. These findings suggest that ovarian hormone exposure during adolescence does not have long-term effects on anxiety-related responses in female rats.

Gender Dysphoria in Adults: An Overview and Primer for Psychiatrists

(Copyright © William Byne et al. 2018; Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.).

Two-factor specification of apoptosis: TGF-β signaling acts cooperatively with ecdysone signaling to induce cell- and stage-specific apoptosis of larval neurons during metamorphosis in Drosophila melanogaster

Developmentally regulated programmed cell death (PCD) is one of the key cellular events for precise controlling of neuronal population during postembryonic development of the central nervous system. Previously we have shown that a group of corazonin-producing peptidergic neurons (vCrz) undergo apoptosis in response to ecdysone signaling via ecdysone receptor (EcR)-B isoforms and Ultraspiracle during early phase of metamorphosis. Further utilizing genetic, transgenic, and mosaic analyses, we have found that TGF-β signaling mediated by a glia-produced ligand, Myoglianin, type-I receptor Baboon (particularly Babo-A isoform) and dSmad2, is also required autonomously for PCD of the vCrz neurons. Our studies show that TGF-β signaling is not acting epistatically to EcR or vice versa. We also show that ectopic expression of a constitutively active phosphomimetic form of dSmad2 (dSmad2^PM) is capable of inducing premature death of vCrz neurons in larva but not other larval neurons. Intriguingly, the dSmad2^PM-mediated killing is completely suppressed by coexpression of a dominant-negative form of EcR (EcR^DN), suggesting that EcR function is required for the proapoptotic dSmad2^PM function. Based on these data, we suggest that TGF-β and ecdysone signaling pathways act cooperatively to induce vCrz neuronal PCD. We propose that this type of two-factor authentication is a key developmental strategy to ensure the timely PCD of specific larval neurons during metamorphosis.

Nature and nurture of sexual partner preference: Teachings from prenatal administration of acetaminophen in male rats

The organizational-activational hypothesis indicates that activation of adult sexual behavior in males depends on organization of the masculine brain during the perinatal sensitive period. In the medial preoptic area such masculinization depends on a neuroendocrine cascade that includes exposure to testosterone, aromatization to estradiol, activation of estrogen receptors, synthesis of cyclooxygenase (COX), increase of prostaglandins, release of glutamate, and activation of AMPA receptors that result in the formation of more dendritic spines. Thus, in the present study we assessed the sexual partner preference (SPP) of adult male rats prenatally treated with acetaminophen (APAP), an analgesic/antipyretic drug that inhibits COX-2 and is commonly used and prescribed during pregnancy. Female rats received either saline (2 ml/kg s.c.) or APAP (50 mg/kg s.c.) every 12 h, during days 16-20 of pregnancy. At postnatal day PD60 half of the male offspring were exposed to sexual experience with receptive females during 5 trials, and the other half remained sexually naïve. At PD90 all them were tested for SPP with one sexually receptive female and one stud male. The results indicated that only APAP-naïve males failed to display SPP. However, APAP-experienced males displayed SPP for females. We discuss the effects of prenatal APAP in the disruption of unconditioned responses towards females (nature mechanisms), and the effects of sexual experience (nurture mechanisms) in the development of conditioned heterosexual preference.

Puberty drives fear learning during adolescence

Risk for adverse outcomes, including the onset of mental illness, increases during adolescence. This increase may be linked to both new exposures, such as violence at home or in the community, or to physiological changes driven by puberty. There are significant sex differences in adolescent risk, for instance, anxiety disorders are significantly more prevalent in girls than boys. Fear learning is linked to mental health and may develop during adolescence, but the role of puberty in adolescent-specific change has not yet been systematically evaluated. We conducted a longitudinal study of fear learning that tested fear-potentiated startle (FPS) in 78 children (40 girls) aged 8-16 years. Participants completed two to three visits that included a differential fear conditioning task and self-report of both pubertal status and violence exposure. We tested for effects of sex, pubertal status, and violence exposure on FPS over time with latent growth curve models. We also examined the association between FPS and later anxiety symptoms. We found significant changes in FPS to the threat cue, but not the safety cue, across visits. Higher pubertal status was significantly associated with increased FPS to threat cues at each visit, whereas sex and violence exposure were not. FPS to threat during the baseline visit also predicted later anxiety symptoms. These findings suggest that puberty drives increased fear response to threat cues similarly for girls and boys, and that this effect may not be significantly impacted by individual differences in violence exposure during early adolescence.

Beyond the challenge hypothesis: The emergence of the dual-hormone hypothesis and recommendations for future research

The challenge hypothesis makes specific predictions about the association between testosterone and status-seeking behaviors, but the findings linking testosterone to these behaviors are often inconsistent. The dual-hormone hypothesis was developed to help explain these inconsistencies. Specifically, according to this hypothesis, testosterone's association with status-seeking behavior depends on levels of cortisol. Here, we (1) describe the dual-hormone hypothesis in relation to the challenge hypothesis; (2) review recent studies that tested the dual-hormone hypothesis as well as meta-scientific evidence of heterogeneous dual-hormone findings across studies; (3) discuss potential explanations for this heterogeneity, including methodological considerations, contextual factors, and individual differences; and (4) provide recommendations for new work aimed at testing and extending the dual-hormone hypothesis.

Assessing the Evidence of Micronutrients on Depression among Children and Adolescents: An Evidence Gap Map

There is some evidence indicating that nutrition may have the ability to prevent, treat, and/or influence the severity of depression. The aims of this evidence gap map (EGM) are to provide an overview and to determine evidence gaps in the existing research on micronutrients and their impact on depression among children and adolescents. We conducted a comprehensive search in multiple databases of primary and secondary literature assessing the impact of micronutrients on depression-related outcomes such as unipolar depression, major depressive disorders, dysthymia, acute depression, and mood disorders. Abstracts and full-text articles were dual-screened based on predefined eligibility criteria. A total of 30 primary research publications were included in the EGM. About 47% of included studies focused on late adolescents (15-19 y), ∼40% on early adolescents (10-14 y), and ∼13% on children aged 6-9 y. Among the included studies, 8 studies examined a single micronutrient intervention and 22 studies examined micronutrient concentrations (either intake or serum), and their impact on depression. The most frequently studied micronutrients were vitamin D (n = 8), zinc (n = 8), iron (n = 6), folate (n = 7), and vitamin B-12 (n = 5). More longitudinal studies and trials are needed to determine the role of micronutrients in the etiology and treatment of depression among children and adolescents.

The effects of gastrointestinal symptoms on structural grey matter volume in youth

Previous neuroimaging studies have examined the association between changes in brain structure and gastrointestinal symptoms (GIS), seen in disorders such as Irritable Bowel Syndrome and Irritable Bowel Disease. Studies in adults have found changes in white and grey matter volume (GMV) in patients with various gastrointestinal disorders. However, it is unclear whether GIS-related structural changes in the brain are limited to adults or could be present throughout the lifespan. Given that gastrointestinal disorders are typically diagnosed between 4 and 18 years old, we investigated GIS-induced morphological changes in pre-adolescents (8-10), adolescents (12-16 years) and young adults (17-21 years). Using a voxel-based morphometry (VBM) analysis, we compared regional grey matter volume (GMV) between participants with GIS and controls, using structural brain images from the Philadelphia Neurodevelopmental Cohort (PNC) database. A total of 211 participants (107 participants with GISs and 104 control participants) who had undergone structural magnetic resonance imaging were analysed. VBM analysis was used to objectively analyse GMV across the whole brain and compare between participants with GIS and controls. Participants experiencing GIS showed smaller GMV in regions within the limbic system/basal ganglia (bilateral caudate, bilateral ventral hippocampus, bilateral amygdala and bilateral superior orbital frontal cortex), and larger GMV in regions within the pain-matrix (thalamus, bilateral putamen, right mid-frontal gyrus) compared to controls. These differences were most prominent in the adolescent and young adult groups compared to pre-adolescents. In conclusion, the structural differences found in participants with GIS support the need for further research into the neurophysiological impact of these symptoms.

Adaptive reshaping of the hormonal phenotype after social niche transition in adulthood

Phenotypic plasticity allows individuals to adjust traits to the environment. Whether long-term adjustments of the phenotype occur during later life stages is largely unknown. To address this question, we examined whether hormonal phenotypes that are shaped by the environment during adolescence can still be reshaped in full adulthood. For this, guinea pig males were either housed in mixed-sex colonies or in heterosexual pairs. In adulthood, males were individually transferred to pair housing with a female. This way, a social niche transition was induced in colony-housed males, but not in pair-housed males. Before transfer, corresponding to findings in adolescence, adult colony-housed males showed significantly higher baseline testosterone levels and lower cortisol responsiveness than pair-housed males. One month after transfer, the hormonal phenotype of colony-housed males was changed towards that of pair-housed males: animals showed comparable baseline testosterone levels and cortisol responsiveness was significantly increased in colony-housed males. This endocrine readjustment builds the basis for an adaptive behavioural tactic in the new social situation. Thus, an adaptive change of the behavioural phenotype may still occur in adulthood via modification of underlying mechanisms. This suggests a greater role for developmental plasticity in later life stages than is commonly presumed.

Androgens and the developing hippocampus

The hippocampus is central to spatial learning and stress responsiveness, both of which differ in form and function in males versus females, yet precisely how the hippocampus contributes to these sex differences is largely unknown. In reproductively mature individuals, sex differences in the steroid hormone milieu undergirds many sex differences in hippocampal-related endpoints. However, there is also evidence for developmental programming of adult hippocampal function, with a central role for androgens as well as their aromatized byproduct, estrogens. These include sex differences in cell genesis, synapse formation, dendritic arborization, and excitatory/inhibitory balance. Enduring effects of steroid hormone modulation occur during two developmental epochs, the first being the classic perinatal critical period of sexual differentiation of the brain and the other being adolescence and the associated hormonal changes of puberty. The cellular mechanisms by which steroid hormones enduringly modify hippocampal form and function are poorly understood, but we here review what is known and highlight where attention should be focused.

The age-dependent effect of pre-pubertal castration on anxiety-like behaviour in male rats

Adolescence is considered to be a critical period of sex hormone action (re)organising the brain and determining the behavioural phenotype. Such organisational effects in the brain might be the cause of sex differences in some behavioural features. In this experiment, we aimed to examine the role of pubertal sex hormones in development of anxiety in male rats. Male rats underwent gonadectomy prior to puberty onset, and were tested for explorative and anxiety-like behaviour in adolescence as well as in young adulthood. In adolescence, but not in adulthood, gonadectomised rats spend by 50% more time (p < .05) in the centre zone of the open-field than sham-operated counterparts. Young adult gonadectomised rats showed approximately 1.5-fold greater exploratory activity, in both open field (p < .001) and elevated plus maze (p < .01), in comparison with young adult control rats. Our results indicate that pre-pubertal castration may have test-specific anxiolytic effect in adolescent male rats, and it may attenuate the decline in explorative behaviour in young adult males. These differences in short- and long-term effects of gonadectomy could explain some contradictory results of previous studies on the role of testosterone in anxiety-like behaviour of male rodents. Thus, the age-specific consequences of pre-pubertal hormone deprivation should be considered.

Sexes on the brain: Sex as multiple biological variables in the neuronal control of feeding

Neuronal interactions at the level of vagal, homeostatic, and hedonic circuitry work to regulate the neuronal control of feeding. This integrative system appears to vary across sex and gender in the animal and human worlds. Most feeding research investigating these variations across sex and gender focus on how the organizational and activational mechanisms of hormones contribute to these differences. However, in limited studies spanning both the central and peripheral nervous systems, sex differences in feeding have been shown to manifest not just at the level of the hormonal, but also at the chromosomal, epigenetic, cellular, and even circuitry levels to alter food intake. In this review, we provide a brief orientation to the current understanding of how these neuronal systems interact before dissecting selected studies from the recent literature to exemplify how feeding physiology at all levels can be affected by the various components of sex.

Teenage dogs? Evidence for adolescent-phase conflict behaviour and an association between attachment to humans and pubertal timing in the domestic dog

The relationship between parent and child changes around adolescence, with children believed to have: (i) an earlier puberty if they have less secure attachments to their carer; (ii) a phase of increased conflict behaviour toward their carer; and (iii) heightened conflict behaviour when carer attachments are less secure. We find support for analogous associations in adolescent dogs based on behaviour and reproductive timing of potential guide dogs. Bitches with behaviour indicative of insecure attachments pre-adolescence became reproductively capable earlier. Providing the first empirical evidence to our knowledge in support of adolescent-phase behaviour in dogs, we found a passing phase of carer-specific conflict-like behaviour during adolescence (reduced trainability and responsiveness to commands), an effect that was more pronounced in dogs with behaviour indicative of less secure attachments. These results indicate a possibility for cross-species influence on reproductive development and highlight adolescence as a vulnerable time for dog–owner relationships.

Timing of peripubertal steroid exposure predicts visuospatial cognition in men: Evidence from three samples

Experiments in male rodents demonstrate that sensitivity to the organizational effects of steroid hormones decreases across the pubertal window, with earlier androgen exposure leading to greater masculinization of the brain and behavior. Similarly, some research suggests the timing of peripubertal exposure to sex steroids influences aspects of human psychology, including visuospatial cognition. However, prior studies have been limited by small samples and/or imprecise measures of pubertal timing. We conducted 4 studies to clarify whether the timing of peripubertal hormone exposure predicts performance on male-typed tests of spatial cognition in adulthood. In Studies 1 (n = 1095) and 2 (n = 173), we investigated associations between recalled pubertal age and spatial cognition in typically developing men, controlling for current testosterone levels in Study 2. In Study 3 (n = 51), we examined the relationship between spatial performance and the age at which peripubertal hormone replacement therapy was initiated in a sample of men with Isolated GnRH Deficiency. Across Studies 1-3, effect size estimates for the relationship between spatial performance and pubertal timing ranged from. -0.04 and -0.27, and spatial performance was unrelated to salivary testosterone in Study 2. In Study 4, we conducted two meta-analyses of Studies 1-3 and four previously published studies. The first meta-analysis was conducted on correlations between spatial performance and measures of the absolute age of pubertal timing, and the second replaced those correlations with correlations between spatial performance and measures of relative pubertal timing where available. Point estimates for correlations between pubertal timing and spatial cognition were -0.15 and -0.12 (both p < 0.001) in the first and second meta-analyses, respectively. These associations were robust to the exclusion of any individual study. Our results suggest that, for some aspects of neural development, sensitivity to gonadal hormones declines across puberty, with earlier pubertal hormone exposure predicting greater sex-typicality in psychological phenotypes in adulthood. These results shed light on the processes of behavioral and brain organization and have implications for the treatment of IGD and other conditions wherein pubertal timing is pharmacologically manipulated.

Sexual differentiation of brain and other tissues: Five questions for the next 50 years

This paper is part of the celebration of the 50th anniversary of founding of the journal Hormones and Behavior, the official journal of the Society for Behavioral Neuroendocrinology. All sex differences in phenotypic development stem from the sexual imbalance in X and Y chromosomes, which are the only known differences in XX and XY zygotes. The sex chromosome genes act within cells to cause differences in phenotypes of XX and XY cells throughout the body. In the gonad, they determine the type of gonad, leading to differences in secretion of testicular vs. ovarian hormones, which cause further sex differences in tissue function. These current ideas of sexual differentiation are briefly contrasted with a hormones-only view of sexual differentiation of the last century. The multiple, independent action of diverse sex-biasing agents means that sex-biased factors can be synergistic, increasing sex differences, or compensatory, making the two sexes more equal. Several animal models have been fruitful in demonstrating sex chromosome effects, and interactions with gonadal hormones. MRI studies of human brains demonstrate variation in brain structure associated with both differences in gonadal hormones, and in the number of X and Y chromosomes. Five unanswered questions are posed as a challenge to future investigators to improve understanding of sexual differentiation throughout the body.

Effects of 17β-trenbolone exposure on sex hormone synthesis and social behaviours in adolescent mice

17β-Trenbolone (17β-TBOH) is an endocrine disruptor that has been widely reported in aquatic organisms. However, little is known about the effect of 17β-TBOH on mammals, particularly on the development of adolescents. Through a series of behavioural experiments, exposure to at 80 μg kg ^-1 d ^-1 and 800 μg kg ^-1 d ^-1 17β-TBOH during puberty (from PND 28 to 56, male mice) increased anxiety-like behaviours. Exposure to the low dose of 80 μg kg ^-1 d ^-1 resulted in a clear social avoidance behaviour in mice. The two doses affected testicular development and endogenous androgen synthesis in male mice. In addition, 17β-TBOH exposure altered the differentiation of oligodendrocytes and the formation of the myelin sheath in the medial prefrontal cortex (mPFC). These results reveal the effects of 17β-TBOH on the behaviours, gonadal and neurodevelopment of adolescent mammals. In addition, the inhibition of the secretion of endogenous hormones and decrease in the formation of the myelin sheath in mPFC may be associated with the 17β-TBOH-induced behavioural changes in mice.

Sex differences in the effects of gonadal hormones on white matter microstructure development in adolescence

Adolescence is characterized by rapid brain development in white matter (WM) that is attributed in part to surges in gonadal hormones. To date, however, there have been few longitudinal investigations relating changes in gonadal hormones and WM development in adolescents. We acquired diffusion-weighted MRI to estimate mean fractional anisotropy (FA) from 10 WM tracts and salivary testosterone from 51 females and 29 males (ages 9-14 years) who were matched on pubertal stage and followed, on average, for 2 years. We tested whether interactions between sex and changes in testosterone levels significantly explained changes in FA. We found positive associations between changes in testosterone and changes in FA within the corpus callosum, cingulum cingulate, and corticospinal tract in females (all ps<0.05, corrected) and non-significant associations in males. We also collected salivary estradiol from females and found that increases in estradiol were associated with increases in FA in the left uncinate fasciculus (p = 0.04, uncorrected); however, this effect was no longer significant after accounting for changes in testosterone. Our findings indicate there are sex differences in how changes in testosterone relate to changes in WM microstructure of tracts that support impulse control and emotion regulation across the pubertal transition.

Adolescent CB1 receptor antagonism influences subsequent social interactions and neural activity in female rats

We previously demonstrated that repeated exposure to the CB1 receptor antagonist/inverse agonist AM251 in adolescence (PND 30-44) increased social interactions in female rats when tested 48 h after the final exposure to the antagonist. Here, we investigated whether the increased sociality would be present after a longer drug washout period (5 days) in both male and female rats (experiment 1), and sought to identify candidate brain regions that may explain the observed differences in social behaviours between AM251 and vehicle-treated female rats (experiment 2). While drug-free, adolescent AM251 treatment increased social interactions in females and not in males. AM251 female rats had increased neural activity (as measured by the expression of early growth response protein-1; EGR-1) in the nucleus accumbens shell and cingulate gyrus of the medial prefrontal cortex, with no observed differences in EGR-1 expression in the dorsal hippocampus, nucleus accumbens core, or prelimbic and infralimbic subdivisions of the medial prefrontal cortex relative to vehicle rats. Together, these results demonstrate a sex-specific role of adolescent endocannabinoid signalling in the normative development of social behaviours and provide further support for adolescence as a vulnerable period for the effects of altered endocannabinoid signalling.

Within-Family Environment and Cross-Fostering Stress Affect Behavior and Physiology in Wild Cavies (Cavia aperea)

Stability of personality traits is well-documented for a wide variety of animals. However, previous results also suggest that behavioral phenotypes are plastic during early ontogeny and can be adaptively shaped to the social environment. In cavies (Cavia aperea), it has already been documented that the size at birth relative to siblings (size rank) greatly influences various behavioral and physiological traits that last at least until independence. The aim of the current study was (1) to investigate if behavioral and physiological differences between pups of the same litter persist until after independence and influence development long-lasting, (2) to determine the potential plasticity in response to changes in the early within-family environment by cross-fostering pups either to the same, a lower, or a higher size rank in a foster-family. We measured three behavioral traits (number of interactions with a novel object, distance moved in an open field, struggle docility) and two physiological traits (resting metabolic rate and basal cortisol levels). We predicted that cross-fostering into a litter where pups occupy the same size rank would not change the expression of traits. Cross-fostering to a different size rank should not influence the expression of traits if repeatability measures indicate low plasticity. Alternatively, if the traits are plastic, animals should adjust trait expression to fit with the size rank occupied in the foster litter. Initial differences in struggle docility, distance moved in an open field and in baseline cortisol concentration between pups of different size-ranks did not remain stable beyond independence. In addition, we found remarkable plasticity of the measured traits in response to cross-fostering to the same, a smaller or larger size-rank, suggesting that differences between pups are more the result of social constraints leading to adaptive shaping of individual phenotypes within a family. We also found a significant influence of the cross-fostering procedure itself. Cross-fostered individuals were less bold, grew slower and showed elevated resting metabolic rates. This finding suggests a cautious interpretation of previous cross-fostering studies and stresses the need for proper control groups to reliably separate the effect of cross-fostering per se from those induced by an experimental treatment.

Prenatal sex hormones and behavioral outcomes in children

Abnormal sex hormone levels in utero have been associated with child behavioral problems, but it is unclear if normal variation in prenatal sex hormones is associated with subsequent behavior in childhood. We assessed maternal sex hormones, including serum estrone (E1), estradiol (E2), estriol (E3), free testosterone (FT), and total testosterone (TT), during early pregnancy (gestational week 6-21 (mean = 11.1)) and evaluated child behavior at ages 4-5 using the Behavioral Assessment System for Children (BASC-2) and Social Responsiveness Scale (SRS-2) in 404 mother/child pairs (211 girls, 193 boys) within The Infant Development and Environment Study, a multi-site pregnancy cohort study. Associations between hormones and composite scores were evaluated using multiple linear regressions in both sexes combined, and separate models assessed effect modification by sex with the addition of interaction terms. A 10-fold increase in maternal FT or TT was associated in both sexes with a 4.3-point (95 % CI: 0.5, 8.2) or 4.4-point (0.8, 8.0) higher BASC-2 internalizing composite T score, respectively. In addition, a 10-fold increase in FT or TT was associated with a 3.8-point (0.04, 7.5) or 4.0-point (0.5, 7.5) higher behavioral symptoms index composite score. In models evaluating effect modification by sex, a 10-fold increase in E1 was associated with a 4.3-point (1.2, 7.4) decrease in adaptive skills composite score in girls only (interaction p = 0.04). We observed associations between testosterone and internalizing behaviors and behavioral symptoms index in both sexes, as well as a female-specific association between E1 and adaptive skills. Sex hormones during pregnancy may play a key role in influencing later-life behavior, and additional studies should further examine different periods of susceptibility to hormonal signals.

Early menarche as a risk factor for suicidal ideation in girls: The Korea youth risk behavior web-based survey

Puberty, at which point girls experience menarche, is a biologically and psychologically unstable period. This study investigated the association between early menarche and suicidal ideation in girls. This study analyzed data from approximately 35,000 girls from the Korea Youth Risk Behavior Web-Based Survey every year from 2011 to 2015. The odds ratios of suicidal ideation were compared between the early and average menarche groups. Generally, the odds ratios of suicidal ideation in girls with early menarche were significantly higher than those with average menarche.

Exploratory Evidence of Sex-Dimorphic Associations of the Ulna-to-Fibula Ratio, a Potential Marker of Pubertal Sex Steroid Exposure, with the Implicit Need for Power

Objectives

We propose a novel marker of pubertal organizing hormone effects on the brain, long bone length, and assess its relationships to implicit motives, especially the implicit need for power (nPower).

Methods

In a partly exploratory approach, we tested 126 participants (after exclusions; 53 men, 73 women), in a cross-sectional design using the Picture-Story Exercise (nPower, activity inhibition), standard anthropometric measurements (BMI, height), and calipers to assess bone length of the ulna and fibula.

Results

Results indicated that a sex-dimorphic (d = 0.55) Ulna-to-Fibula Ratio (UFR), which is independent of body height, best captures the variance in our data. While we did not find bivariate relationships between long bone length and nPower, a sex-dimorphic interaction of nPower and activity inhibition on UFR-asymmetry (UFRr-l; right versus left UFR) emerged. High UFRr-l scores were related to the inhibited power motive (high nPower, high activity inhibition) in men, while for women the pattern was (non-significantly) reversed. In addition, UFR was predicted by a sex-dimorphic effect of nPower, with low UFR scores being associated with a higher nPower in men and a tendency for high UFR scores being related to lower nPower in women.

Conclusions

We discuss our results regarding UFR’s potential as a sex-dimorphic marker of the organizing effects of pubertal steroid hormones on the motivational brain beyond hand and face parameters routinely used in current research. Finally, we examine how our findings fit recent results obtained for the relationship between 2D:4D digit ratio or facial width-to-height ratio and nPower.

Becoming a mother entails anatomical changes in the ventral striatum of the human brain that facilitate its responsiveness to offspring cues

In mothers, offspring cues are associated with a powerful reinforcing value that motivates maternal care. Animal studies show that this is mediated by dopamine release into the nucleus accumbens, a core component of the brain's reward system located in the ventral striatum (VStr). The VStr is also known to respond to infant signals in human mothers. However, it is unknown whether pregnancy modifies the anatomy or functionality of this structure, and whether such modifications underlie its strong reactivity to offspring cues. Therefore, we analyzed structural and functional neuroimaging data from a unique pre-conception prospective cohort study involving first-time mothers investigated before and after their pregnancy as well as nulliparous control women scanned at similar time intervals. First, we delineated the anatomy of the VStr in each subject's neuroanatomical space and examined whether there are volumetric changes in this structure across sessions. Then, we tested if these changes could predict the mothers' brain responses to visual stimuli of their infants. We found decreases in the right VStr and a trend for left VStr reductions in the women who were pregnant between sessions compared to the women who were not. Furthermore, VStr volume reductions across pregnancy were associated with infant-related VStr responses in the postpartum period, with stronger volume decreases predicting stronger functional activation to offspring cues. These findings provide the first indications that the transition to motherhood renders anatomical adaptations in the VStr that promote the strong responsiveness of a mother's reward circuit to cues of her infant.