Twin models of environmental and genetic influences on pubertal development, salivary testosterone, and estradiol in adolescence

Fathers and sons, mothers and daughters: Sex-specific genetic architecture for fetal testosterone in a wild mammal

Testosterone plays a critical role in mediating fitness-related traits in many species. Although it is highly responsive to environmental and social conditions, evidence from several species show a heritable component to its individual variation. Despite the known effects that in utero testosterone exposure have on adult fitness, the heritable component of individual testosterone variation in fetuses is mostly unexplored. Furthermore, testosterone has sex-differential effects on fetal development, i.e., a specific level may be beneficial for male fetuses but detrimental for females, producing sexual conflict. Such sexual conflict may be resolved by the evolution of a sex-specific genetic architecture of the trait. Here, we quantified fetal testosterone levels in a wild species, free-ranging nutrias (Myocastor coypus) using hair-testing and estimated testosterone heritability between parent and offspring from the same and opposite sex. We found that in utero accumulated hair testosterone levels were heritable between parents and offspring of the same sex. Moreover, there was a low additive genetic covariance between the sexes, and a low cross-sex genetic correlation, suggesting a potential for sex-specific trait evolution, expressed early on, in utero.

Genetic correlations of alcohol consumption and alcohol use disorder with sex hormone levels in females and males

Background

Alcohol consumption behaviors and alcohol use disorder risk and presentation differ by sex, and these complex traits are associated with blood concentrations of the steroid sex hormones, testosterone and estradiol, and their regulatory binding proteins, sex hormone binding globulin (SHBG) and albumin. Genetic variation is associated with alcohol consumption and alcohol use disorder, as well as levels of steroid sex hormones and their binding proteins.

Methods

To assess the contribution of genetic factors to previously described phenotypic associations between alcohol-use traits and sex-hormone levels, we estimated genetic correlations (rg) using summary statistics from prior published, large sample size genome-wide association studies (GWAS) of alcohol consumption, alcohol dependence, testosterone, estradiol, SHBG, and albumin.

Results

For alcohol consumption, we observed positive genetic correlation (i.e. genetic effects in the same direction) with total testosterone in males (rg = 0.084, p = 0.007) and trends toward positive genetic correlation with bioavailable testosterone (rg = 0.060, p = 0.084) and SHBG in males (rg = 0.056, p = 0.086) and with albumin in a sex-combined cohort (rg = 0.082, p = 0.015); however in females, we observed positive genetic correlation with SHBG (rg = 0.089, p = 0.004) and a trend toward negative genetic correlation (i.e. genetic effects in opposite directions) with bioavailable testosterone (rg = -0.064, p = 0.032). For alcohol dependence, we observed a trend toward negative genetic correlation with total testosterone in females (rg = -0.106, p = 0.024) and positive genetic correlation with BMI-adjusted SHBG in males (rg = 0.119, p = 0.017). Several of these genetic correlations differed between females and males and were not in the same direction as the corresponding phenotypic associations.

Conclusions

Findings suggest that shared genetic effects may contribute to positive associations of alcohol consumption with albumin in both sexes, as well as positive associations between alcohol consumption and bioavailable testosterone and between alcohol dependence and SHBG in males. However, relative contributions of heritable and environmental factors to associations between alcohol-use traits and sex-hormone levels may differ by sex, with genetic factors contributing more in males and environmental factors contributing more in females.

Peripubertal Alterations of Leptin Levels in Patients with Autism Spectrum Disorder and Elevated or Normal Body Weight

Leptin, which plays a key role in energy homeostasis, is known as a neurotrophic factor possibly linking nutrition and neurodevelopment. Available data on the association between leptin and autism spectrum disorder (ASD) are confusing. The aim of this study was to explore whether plasma levels of leptin in pre- and post-pubertal children with ASD and/or overweightness/obesity differ from those of BMI- and age-matched healthy controls. Leptin levels were determined in 287 pre-pubertal children (mean age 8.09 years), classified as follows: ASD with overweightness/obesity (ASD+/Ob+); ASD without overweightness/obesity (ASD+/Ob-); non-ASD with overweightness/obesity (ASD-/Ob+); non-ASD without overweightness/obesity (ASD-/Ob-). The assessment was repeated in 258 of the children post-pubertally (mean age 14.26 years). There were no significant differences in leptin levels either before or after puberty between ASD+/Ob+ and ASD-/Ob+ or between ASD+/Ob- and ASD-/Ob-, although there was a strong trend toward significance for higher pre-pubertal leptin levels in ASD+/Ob- than in ASD-/Ob-. Post-pubertal leptin levels were significantly lower than pre-pubertal levels in ASD+/Ob+, ASD-/Ob+, and ASD+/Ob- and higher in ASD-/Ob-. Leptin levels, elevated pre-pubertally in the children with overweightness/obesity as well as in children with ASD and normal BMI, decrease with age, in contrast to the increasing leptin levels in healthy controls.

Influence of gonadal steroids on cortical surface area in infancy

Sex differences in the human brain emerge as early as mid-gestation and have been linked to sex hormones, particularly testosterone. Here, we analyzed the influence of markers of early sex hormone exposure (polygenic risk score (PRS) for testosterone, salivary testosterone, number of CAG repeats, digit ratios, and PRS for estradiol) on the growth pattern of cortical surface area in a longitudinal cohort of 722 infants. We found PRS for testosterone and right-hand digit ratio to be significantly associated with surface area, but only in females. PRS for testosterone at the most stringent P value threshold was positively associated with surface area development over time. Higher right-hand digit ratio, which is indicative of low prenatal testosterone levels, was negatively related to surface area in females. The current work suggests that variation in testosterone levels during both the prenatal and postnatal period may contribute to cortical surface area development in female infants.

Acquisition and establishment of the oral microbiota

Acquisition and establishment of the oral microbiota occur in a dynamic process over various stages and involve close and continuous interactions with the host and its environment. In the present review, we discuss the stages of this process in chronological order. We start with the prenatal period and address the following questions: ‘Is the fetus exposed to maternal microbiota during pregnancy?’ and ‘If so, what is the potential role of this exposure?’ We comment on recent reports of finding bacterial DNA in placenta during pregnancies, and provide current views on the potential functions of prenatal microbial encounters. Next, we discuss the physiological adaptations that take place in the newborn during the birth process and the effect of this phase of life on the acquisition of the oral microbiota. Is it really just exposure to maternal vaginal microbes that results in the difference between vaginally and Cesarian section‐born infants? Then, we review the postnatal phase, in which we focus on transmission of microbes, the intraoral niche specificity, the effects of the host behavior and environment, as well as the role of genetic background of the host on shaping the oral microbial ecosystem. We discuss the changes in oral microbiota during the transition from deciduous to permanent dentition and during puberty. We also address the finite knowledge on colonization of the oral cavity by microbes other than the bacterial component. Finally, we identify the main outstanding questions that limit our understanding of the acquisition and establishment of a healthy microbiome at an individual level.

GWAS of three molecular traits highlights core genes and pathways alongside a highly polygenic background

Genome-wide association studies (GWAS) have been used to study the genetic basis of a wide variety of complex diseases and other traits. We describe UK Biobank GWAS results for three molecular traits-urate, IGF-1, and testosterone-with better-understood biology than most other complex traits. We find that many of the most significant hits are readily interpretable. We observe huge enrichment of associations near genes involved in the relevant biosynthesis, transport, or signaling pathways. We show how GWAS data illuminate the biology of each trait, including differences in testosterone regulation between females and males. At the same time, even these molecular traits are highly polygenic, with many thousands of variants spread across the genome contributing to trait variance. In summary, for these three molecular traits we identify strong enrichment of signal in putative core gene sets, even while most of the SNP-based heritability is driven by a massively polygenic background.

Puberty and the Evolution of Developmental Science

In recent decades, theoretical and methodological advances have operated synergistically to advance understanding of puberty and prompt increasingly comprehensive models that engage with the temporal, psychosocial, and biological dimensions of this maturational milepost. This integrative overview discusses these theoretical and methodological advances and their implications for research and intervention to promote human development in the context of changing maturational schedules and massive ongoing social transformations.

Developmental differences in reward sensitivity and sensation seeking in adolescence: Testing sex-specific associations with gonadal hormones and pubertal development

Sensation seeking has been found to increase, on average, from childhood to adolescence. Developmental scientists have hypothesized that this change could be driven by the rise of gonadal hormones at puberty, which affect reward-related processing in the brain. In a large, age-heterogeneous, population-based sample of adolescents and young adults (N = 810; ages 13-20 years), we tested for sex-specific associations between age, self-reported pubertal development, gonadal hormones (estradiol and testosterone) as measured in saliva, reward sensitivity as measured by a multivariate battery of in-laboratory tasks (including the Iowa gambling task, balloon analogue risk task, and stoplight task), and self-reported sensation seeking. Reward sensitivity was more strongly associated with sensation seeking in males than females. For both males and females, reward sensitivity was unrelated to age but was higher among those who reported more advanced pubertal development. There were significant sex differences in the effects of self-reported pubertal development on sensation seeking, with a positive association evident in males but a negative association in females. Moreover, gonadal hormones also showed diverging associations with sensation seeking-positive with testosterone but negative with estradiol. Overall, the results indicate that sensation seeking among adolescents and young adults depends on a complex constellation of developmental influences that operate via sex-specific mechanisms. (PsycINFO Database Record