The role of testosterone in coordinating male life history strategies: The moderating effects of the androgen receptor CAG repeat polymorphism

Men's physical health and life history transitions in the Philippines: Evidence for 'marital selection' but not protective effects of partnering and fatherhood

In Euro-American societies, married people typically have lower overall risks for total mortality and for certain chronic conditions compared to non-married people. However, people becoming partnered and parents also tend to gain weight in Euro-American settings. Few studies have tested whether links between physical health and life history status translate to other cultural contexts where the socio-ecological dynamics of family life may differ. This limits the application of these insights to men's well-being in global public health. To help address this gap, we drew on a large, long-running birth cohort study of Filipino men, using data collected at three waves between 2005 and 2014 when men were 21.5-30.5 years old (N = 607, obs. = 1760). We tested for the effects of the transition to partnering (marriage/cohabitation) and fatherhood on men's physical health (waist circumference, fat-free mass index, and grip strength). Men becoming partnered or partnered fathers (P/PF) had comparable longitudinal physical health trajectories to men remaining single non-fathers. However, men who became P/PF by their mid 20s had higher fat-free mass index values than single non-fathers at each wave, with the largest effect observed when all men were single non-fathers at baseline. Men who became P/PF by their early 30s were also stronger than the reference group at baseline. Thus, men who were more muscular and stronger at baseline were more likely to transition to P/PF status, consistent with a 'marital selection' model. In complementary analyses, men did not exhibit adverse health effects when they became partnered fathers as young adults or parents to infants, respectively. These findings suggest that links between health and life history transitions in this setting differ from those commonly observed in Euro-American societies. While transitions to marriage and fatherhood are promising windows for interventions to improve men's health, our results highlight the importance of tailoring such approaches to local dynamics.

Evidence for an adolescent sensitive period to family experiences influencing adult male testosterone production

SignificanceTestosterone influences how animals devote energy and time toward reproduction, including opposing demands of mating and competition versus parenting. Reflecting this, testosterone often declines in new fathers and lower testosterone is linked to greater caregiving. Given these roles, there is strong interest in factors that affect testosterone, including early-life experiences. In this multidecade study, Filipino sons whose fathers were present and involved with raising them when they were adolescents had lower testosterone when they later became fathers, compared to sons whose fathers were present but uninvolved or were not coresident. Sons' own parenting behaviors did not explain these patterns. These results connect key social experiences during adolescence to adult testosterone, and point to possible intergenerational effects of parenting style.

Neither environmental unpredictability nor harshness predict reliance on alloparental care among families in Cebu, Philippines

Alloparental caregiving is key to humans' highly flexible reproductive strategies. Across species and across societies, alloparental care is more common in harsh and/or unpredictable environments (HUEs). Currently, however, it is unclear whether HUEs predict intra-population variation in alloparental care, or whether early life HUEs might predict later alloparental care use in adulthood, consistent with adaptive developmental plasticity. We test whether harshness measures (socioeconomic status (SES), environmental hygiene, crowding) and unpredictability measures (parental unemployment, paternal absence, household moves) predicted how much alloparental assistance families in Cebu, Philippines received, in a multigenerational study with data collected across four decades. Though worse environmental hygiene predicted more concurrent alloparental care in 1994, we found little evidence that HUEs predict within-population variation in alloparental care in this large-scale, industrialized society. Indeed, less-crowded conditions and higher SES predicted more alloparental care, not less, in the 1980s and in 2014 respectively, while paternal absence in middle childhood predicted less reliance on alloparental care in adulthood. In this cultural context, our results generally do not provide support for the translation of interspecific or intersocietal patterns linking HUEs and alloparental care to intra-population variation in alloparental care, nor for the idea that a reproductive strategy emphasizing alloparental care use may be preceded by early life HUEs.

Epigenetic regulation of 5α reductase-1 underlies adaptive plasticity of reproductive function and pubertal timing

Background

Women facing increased energetic demands in childhood commonly have altered adult ovarian activity and shorter reproductive lifespan, possibly comprising a strategy to optimize reproductive success. Here, we sought to understand the mechanisms of early-life programming of reproductive function, by integrating analysis of reproductive tissues in an appropriate mouse model with methylation analysis of proxy tissue DNA in a well-characterized population of Bangladeshi migrants in the UK. Bangladeshi women whose childhood was in Bangladesh were found to have later pubertal onset and lower age-matched ovarian reserve than Bangladeshi women who grew-up in England. Subsequently, we aimed to explore the potential relevance to the altered reproductive phenotype of one of the genes that emerged from the screens.

Results

Of the genes associated with differential methylation in the Bangladeshi women whose childhood was in Bangladesh as compared to Bangladeshi women who grew up in the UK, 13 correlated with altered expression of the orthologous gene in the mouse model ovaries. These mice had delayed pubertal onset and a smaller ovarian reserve compared to controls. The most relevant of these genes for reproductive function appeared to be SRD5A1, which encodes the steroidogenic enzyme 5α reductase-1. SRD5A1 was more methylated at the same transcriptional enhancer in mice ovaries as in the women’s buccal DNA, and its expression was lower in the hypothalamus of the mice as well, suggesting a possible role in the central control of reproduction. The expression of Kiss1 and Gnrh was also lower in these mice compared to controls, and inhibition of 5α reductase-1 reduced Kiss1 and Gnrh mRNA levels and blocked GnRH release in GnRH neuronal cell cultures. Crucially, we show that inhibition of this enzyme in female mice in vivo delayed pubertal onset.

Conclusions

SRD5A1/5α reductase-1 responds epigenetically to the environment and its downregulation appears to alter the reproductive phenotype. These findings help to explain diversity in reproductive characteristics and how they are shaped by early-life environment and reveal novel pathways that might be targeted to mitigate health issues caused by life-history trade-offs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01219-6.

Anthropometrics of Estonian children in relation to family disruption: Thrifty phenotype and Trivers-Willard effects

Background and objectives

The thrifty phenotype hypothesis proposes that at resource limitation, the growth of some organs/tissues is selectively spared to preserve more critical ones, such as the brain or lungs. The Trivers–Willard hypothesis (TWH) predicts that boys are more vulnerable in the case of resource limitation than girls. Both hypotheses were tested in children from disrupted families, differing in the extent of deprivation/adversities imposed on them.

Methodology

In a retrospective cohort study in the mid-20th century Estonia (Juhan Aul’s database), different types of orphans and children of divorced parents (treatment groups; n = 106–1401) were compared with children from bi-parental families (control groups; n = 2548–8648) so that children from treatment groups were matched with control children on the basis of sex, age, year of birth, urban versus rural origin and socioeconomic position.

Results

Children in orphanages suffered strong growth suppression, best explained by psychosocial deprivation. Their feet were on average 0.5 SD shorter than the feet of the controls, followed by height, leg/torso ratio and cranial volume that differed from controls by ca 0.4 SD. Weight difference was 0.2 SD units, while body mass index did not differ from controls. The growth of boys and girls in orphanages was suppressed to the same extent. Boys whose mothers were dead were relatively smaller and less masculine than girls from such families. Fathers’ absence was unrelated to growth suppression. Sons of divorced parents had broader shoulders than boys whose fathers were dead.

Conclusions and implications

Prediction of TWH about the greater vulnerability of male growth may hold under some conditions but not universally. Predictions of the thrifty phenotype hypothesis were partly supported: trunk growth was spared at the expense of leg growth; however, no evidence for brain sparing was found. Comparison of children of divorced versus dead fathers may appear useful for indirect assessment of sexual selection on offspring quality.

Lay Summary: Boys and girls in orphanages suffered similarly strong growth suppression, best explained by psychosocial deprivation. Boys whose mothers were dead were relatively smaller and less masculine than girls from such families. The occurrence of sex-specific associations between family structure and children’s growth depends on the type of family disruption.

PolyQ length co-evolution in neural proteins

Intermolecular co-evolution optimizes physiological performance in functionally related proteins, ultimately increasing molecular co-adaptation and evolutionary fitness. Polyglutamine (polyQ) repeats, which are over-represented in nervous system-related proteins, are increasingly recognized as length-dependent regulators of protein function and interactions, and their length variation contributes to intraspecific phenotypic variability and interspecific divergence. However, it is unclear whether polyQ repeat lengths evolve independently in each protein or rather co-evolve across functionally related protein pairs and networks, as in an integrated regulatory system. To address this issue, we investigated here the length evolution and co-evolution of polyQ repeats in clusters of functionally related and physically interacting neural proteins in Primates. We observed function-/disease-related polyQ repeat enrichment and evolutionary hypervariability in specific neural protein clusters, particularly in the neurocognitive and neuropsychiatric domains. Notably, these analyses detected extensive patterns of intermolecular polyQ length co-evolution in pairs and clusters of functionally related, physically interacting proteins. Moreover, they revealed both direct and inverse polyQ length co-variation in protein pairs, together with complex patterns of coordinated repeat variation in entire polyQ protein sets. These findings uncover a whole system of co-evolving polyQ repeats in neural proteins with direct implications for understanding polyQ-dependent phenotypic variability, neurocognitive evolution and neuropsychiatric disease pathogenesis.

Sharing and caring: Testosterone, fathering, and generosity among BaYaka foragers of the Congo Basin

Humans are rare among mammals in exhibiting paternal care and the capacity for broad hyper-cooperation, which were likely critical to the evolutionary emergence of human life history. In humans and other species, testosterone is often a mediator of life history trade-offs between mating/competition and parenting. There is also evidence that lower testosterone men may often engage in greater prosocial behavior compared to higher testosterone men. Given the evolutionary importance of paternal care and heightened cooperation to human life history, human fathers' testosterone may be linked to these two behavioral domains, but they have not been studied together. We conducted research among highly egalitarian Congolese BaYaka foragers and compared them with their more hierarchical Bondongo fisher-farmer neighbors. Testing whether BaYaka men's testosterone was linked to locally-valued fathering roles, we found that fathers who were seen as better community sharers had lower testosterone than less generous men. BaYaka fathers who were better providers also tended to have lower testosterone. In both BaYaka and Bondongo communities, men in marriages with greater conflict had higher testosterone. The current findings from BaYaka fathers point to testosterone as a psychobiological correlate of cooperative behavior under ecological conditions with evolutionarily-relevant features in which mutual aid and sharing of resources help ensure survival and community health.

Changes in prenatal testosterone and sexual desire in expectant couples

During the transition to parenthood (TTP), both women and men report declines in sexual desire, which are thought to reflect an evolutionarily adaptive focus on parenting over mating. New parents also show changes in testosterone, a steroid hormone implicated in both parenting and mating, suggesting that changes in sexual desire may be associated with changes in testosterone. To test these associations, we followed a sample of heterosexual couples expecting their first child across the prenatal period. We examined prenatal changes in testosterone and two forms of sexual desire (solitary, dyadic). Expectant mothers showed prenatal increases in testosterone, and women's higher testosterone was associated with lower dyadic desire. Expectant fathers showed prenatal decreases in testosterone, and declines in men's testosterone were associated with lower dyadic desire. Testosterone was unrelated to men's or women's solitary desire. Our findings provide support for the idea that prenatal changes in testosterone contribute to an evolutionarily adaptive focus on parenting over mating during the TTP.

Testosterone reactivity to competition and competitive endurance in men and women

Transient shifts in testosterone occur during competition and are thought to positively influence dominance behavior aimed at enhancing social status. However, individual differences in testosterone reactivity to status contests have not been well-studied in relation to real-time expressions of competitive behavior among men and women. This research tests the association between changes in endogenous testosterone levels during competition and performance in terms of competitive endurance. Participant sex, social presence, and relative status outcomes (e.g., winning vs. losing) are tested as moderators of this relationship. In two studies, men and women (total N = 398) competed in the competitive will task (timed weight-holding) either individually or in the presence of an opponent (Study 1) or as a team with and without the presence of a competitor team (Study 2). Results showed a positive relationship between testosterone reactivity and performance for men, particularly those who won or ranked highest among their group - with increasing testosterone predicting better performance and decreasing testosterone predicting worse performance. For women, the effect only emerged among individuals who competed in dyads and lost. In Study 2, an exploratory mediation analysis revealed that individual differences in trait dominance predicted both testosterone reactivity to competition and task performance, with testosterone reactivity (moderated by sex and status outcome) partially explaining the direct relationship between dominance-related traits and behavior. Our goal was to examine testosterone reactivity in relation to real-time competitive effort and highlight the potential role of this relationship in explaining how individual differences in trait dominance produce competitive behavior.

Evolutionary life history theory as an organising framework for cohort studies: insights from the Cebu Longitudinal Health and Nutrition Survey

By tracking a group of individuals through time, cohort studies provide fundamental insights into the developmental time course and causes of health and disease. Evolutionary life history theory seeks to explain patterns of growth, development, reproduction and senescence, and inspires a range of hypotheses that are testable using the longitudinal data from cohort studies. Here we review two decades of life history theory-motivated work conducted in collaboration with the Cebu Longitudinal Health and Nutrition Survey (CLHNS), a birth cohort study that enrolled more than 3000 pregnant women in the Philippines in 1983 and has since followed these women, their offspring and grandoffspring. This work has provided evidence that reproduction carries "costs" to cellular maintenance functions, potentially speeding senescence, and revealed an unusual form of genetic plasticity in which the length of telomeres inherited across generations is influenced by reproductive timing in paternal ancestors. Men in Cebu experience hormonal and behavioural changes in conjunction with changes in relationship and fatherhood status that are consistent with predictions based upon other species that practice bi-parental care. The theoretical expectation that early life cues of mortality or environmental unpredictability will motivate a "fast" life history strategy are confirmed for behavioural components of reproductive decision making, but not for maturational tempo, while our work points to a broader capacity for early life developmental calibration of systems like immunity, reproductive biology and metabolism. Our CLHNS findings illustrate the power of life history theory as an integrative, lifecourse framework to guide longitudinal studies of human populations.

Dads: Progress in understanding the neuroendocrine basis of human fathering behavior

We outline the progress on the hormonal basis of human paternal behavior during the past twenty years. Advances in understanding the roles of testosterone, prolactin, oxytocin and vasopressin in fathering behavior are described, along with recent research on hormonal interactions, such as those between testosterone and cortisol, and testosterone and the peptide hormones. In addition, we briefly describe the recent leaps forward in elucidating the neurobiological and neuroendocrine basis of fatherhood, made possible by fMRI technology. Emerging from this literature is a developing and complicated story about fatherhood, highlighting the need to further understand the interplay between behavior, physiology, social context, and individual genetic variation. Given the changing roles of parents in many societies, the continued growth of this research area will provide a strong empirical knowledge base about paternal behavior on which to create policies promoting fathers' involvement in their infants' lives.

Mothers' and fathers' joint profiles for testosterone and oxytocin in a small-scale fishing-farming community: Variation based on marital conflict and paternal contributions

INTRODUCTION

Testosterone and oxytocin are psychobiological mechanisms that interrelate with relationship quality between parents and the quantity and quality of parenting behaviors, thereby affecting child outcomes. Their joint production based on family dynamics has rarely been tested, particularly cross-culturally.

METHODS

We explored family function and salivary testosterone and oxytocin in mothers and fathers in a small-scale, fishing-farming society in Republic of the Congo. Fathers ranked one another in three domains of family life pertaining to the local cultural model of fatherhood.

RESULTS

Fathers who were viewed as better providers had relatively lower oxytocin and higher testosterone than men seen as poorer providers, who had lower testosterone and higher oxytocin. Fathers also had higher testosterone and lower oxytocin in marriages with more conflict, while those who had less marital conflict had reduced testosterone and higher oxytocin. In contrast, mothers in conflicted marriages showed the opposite profiles of relatively lower testosterone and higher oxytocin. Mothers had higher oxytocin and lower testosterone if fathers were uninvolved as direct caregivers, while mothers showed an opposing pattern for the two hormones if fathers were seen as involved with direct care.

CONCLUSIONS

These results shed new light on parents' dual oxytocin and testosterone profiles in a small-scale society setting and highlight the flexibility of human parental psychobiology when fathers' roles and functions within families differ across cultures.

Revisiting the relationships of 2D:4D with androgen receptor (AR) gene and current testosterone levels: Replication study and meta-analyses

The relationships of digit ratio (2D:4D) with the length of AR (CAG)n, and testosterone levels from saliva and blood have been extensively debated over the years. This research including three studies further clarifies such controversies. To do so, we re-examined the relationships between the length of AR (CAG)n, 2D:4D, and current testosterone levels, through replication study and meta-analysis for each study. The results indicate: (a) the length of AR (CAG)n is not significantly associated with 2D:4D; (b) current testosterone levels are not significantly associated with the ratio; and (c) the length is not significantly associated with testosterone levels. Thus, AR (CAG)n and current testosterone levels are not significantly related to 2D:4D at individual level.

A Life History Approach to the Female Sexual Orientation Spectrum: Evolution, Development, Causal Mechanisms, and Health

Women's capacity for sexual fluidity is at least as interesting a phenomenon from the point of view of evolutionary biology and behavioral endocrinology as exclusively homosexual orientation. Evolutionary hypotheses for female nonheterosexuality have failed to fully account for the existence of these different categories of nonheterosexual women, while also overlooking broader data on the causal mechanisms, physiology, ontogeny, and phylogeny of female nonheterosexuality. We review the evolutionary-developmental origins of various phenotypes in the female sexual orientation spectrum using the synergistic approach of Tinbergen's four questions. We also present femme-specific and butch-specific hypotheses at proximate and ultimate levels of analysis. This review article indicates that various nonheterosexual female phenotypes emerge from and contribute to hormonally mediated fast life history strategies. Life history theory provides a biobehavioral explanatory framework for nonheterosexual women's masculinized body morphology, psychological dispositions, and their elevated likelihood of experiencing violence, substance use, obesity, teenage pregnancy, and lower general health. This pattern of life outcomes can create a feedback loop of environmental unpredictability and harshness which destabilizes intrauterine hormonal conditions in mothers, leading to a greater likelihood of fast life history strategies, global health problems, and nonheterosexual preferences in female offspring. We further explore the potential of female nonheterosexuality to function as an alloparental buffer that enables masculinizing alleles to execute their characteristic fast life history strategies as they appear in the female and the male phenotype. Synthesizing life history theory with the female sexual orientation spectrum enriches existing scientific knowledge on the evolutionary-developmental mechanisms of human sex differences.

Testosterone moderates the effects of social support on cardiovascular disease risk factors among older US men

OBJECTIVES

Social support positively affects health through pathways such as shaping intrapersonal emotional and psychological well-being. Lower testosterone often interrelates with psychological and behavioral orientations that are beneficial to participation in emotionally supportive relationships. Yet, little research has considered the ways in which testosterone may contribute to health outcomes related to emotional support.

METHODS

We draw on testosterone, social support data, and cardiovascular disease (CVD)-relevant indicators (inflammatory markers; blood pressure [BP]) from older men (n = 366) enrolled in the National Health and Nutrition Examination Survey, a US nationally representative study. We test whether men's testosterone moderates associations between emotional social support and markers related to CVD risk.

RESULTS

For men with relatively lower testosterone, higher levels of social support predicted lower white blood cell (WBC) counts, consistent with reduced inflammation. In contrast, men with higher testosterone exhibited elevated WBC counts with greater support. In a diverging pattern, men with lower testosterone had higher systolic and diastolic BP with higher support, whereas the slopes for systolic and diastolic BP, respectively, were comparatively flatter for men with higher levels of testosterone.

CONCLUSIONS

We suggest that our findings are theoretically consistent with the idea that testosterone helps shape intrapersonal and interpersonal experiences and perceptions of men's emotional support networks, thereby affecting the health implications of that support. The somewhat divergent results for WBC count vs BP highlight the need for inclusion of other neuroendocrine markers alongside testosterone as well as refined measures of perceived and received support.

More than just mothers: The neurobiological and neuroendocrine underpinnings of allomaternal caregiving

In a minority of mammalian species, mothers depend on others to help raise their offspring. New research is investigating the neuroendocrine mechanisms supporting this allomaternal behavior. Several hormones have been implicated in allomaternal caregiving; however, the role of specific hormones is variable across species, perhaps because allomothering independently evolved multiple times. Brain regions involved in maternal behavior in non-human animals, such as the medial preoptic area, are also critically involved in allomaternal behavior. Allomaternal experience modulates hormonal systems, neural plasticity, and behavioral reactivity. In humans, fatherhood-induced decreases in testosterone and increases in oxytocin may support sensitive caregiving. Fathers and mothers activate similar neural systems when exposed to child stimuli, and this can be considered a global "parental caregiving" network. Finally, early work on caregiving by non-kin (e.g., foster parents) suggests reliance on similar mechanisms as biologically-related parents. This article is part of the 'Parental Brain and Behavior' Special Issue.

Testosterone, fathers as providers and caregivers, and child health: Evidence from fisher-farmers in the Republic of the Congo

Males in vertebrate species with biparental care commonly face a life history trade-off between investing in mating versus parenting effort. Among these males, testosterone is frequently elevated during mating and competition and reduced when males help raise offspring. These physiological patterns may be adaptive, increasing males' fitness through investments in young. However, for some species, including humans, indirect parenting often benefits young but can also involve male competition and risk-taking behavior and may be facilitated by elevated testosterone. Despite potential adaptive functions of biological responses to invested fatherhood, few if any mammalian studies have linked fathers' testosterone to offspring outcomes; no studies in humans have. Using data from a small-scale society of fisher-farmers from the Republic of the Congo, we find that fathers who were rated as better providers by their peers had higher testosterone, compared to other fathers in their community. However, children whose fathers had middle-range T compared to fathers with higher or lower levels had better energetic status (higher BMI; greater triceps skinfold thickness). Fathers' indirect and direct care helped to account for these associations between paternal T and children's energetic profiles. Given that human paternal direct and, especially, indirect care are thought to have been important evolutionarily and remain so in many contemporary societies, these findings help to shed light on the facultative nature of human biological responses to fatherhood and the relevance of these factors to children's well-being.

The Influence of Endogenous Opioids on the Relationship between Testosterone and Romantic Bonding

The endogenous opioid system has received attention and extensive research for its effects on reward, pleasure, and pain. However, relative to other neurochemicals, such as oxytocin, vasopressin and dopamine, the function of opioids in regulating human attachment, sociosexuality, and other aspects of human sociality has not received much consideration. For example, nonapeptides (oxytocin and vasopressin) have been extensively studied in animals and humans for their possible roles in mother-offspring attachment, romantic attachment, fatherhood, and social cognition. Likewise, others have proposed models wherein oxytocin and vasopressin are moderators of the relationship between steroid hormones and human social behaviors. Recently, opioids have generated renewed interest in relation to social pain, and importantly, the brain opioid hypothesis of social attachment (BOTSA), which suggests that endogenous opioids are a key implementer in primate and human bonding, has received some support. Here we focus on romantic bonds by proposing that endogenous opioids are an important mechanism mediating reproductive trade-offs through their inhibitory effects on testosterone production.

Molecular basis of androgen action on human sexual desire

Reproduction is a fundamental process for the species maintenance and the propagation of genetic information. The energy expenditure for mating is overtaken by motivational stimuli, such as orgasm, finely regulated by steroid hormones, gonadotropins, neurotransmitters and molecules acting in the brain and peripheral organs. These functions are often investigated using animal models and translated to humans, where the androgens action is mediated by nuclear and membrane receptors converging in the regulation of both long-term genomic and rapid non-genomic signals. In both sexes, testosterone is a central player of this game and is involved in the regulation of sexual desire and arousal, and, finally, in reproduction through cognitive and peripheral physiological mechanisms which may decline with aging and circadian disruption. Finally, genetic variations impact on reproductive behaviours, resulting in sex-specific effect and different reproductive strategies. In this review, androgen actions on sexual desire are evaluated, focusing on the molecular levels of interaction.

Preliminary evidence that androgen signaling is correlated with men's everyday language

OBJECTIVES

Testosterone (T) has an integral, albeit complex, relationship with social behavior, especially in the domains of aggression and competition. However, examining this relationship in humans is challenging given the often covert and subtle nature of human aggression and status-seeking. The present study aimed to investigate whether T levels and genetic polymorphisms in the AR gene are associated with social behavior assessed via natural language use.

METHODS

We used unobtrusive, behavioral, real-world ambulatory assessments of men in partnered heterosexual relationships to examine the relationship between plasma T levels, variation in the androgen receptor (AR) gene, and spontaneous, everyday language in three interpersonal contexts: with romantic partners, with co-workers, and with their children.

RESULTS

Men's T levels were positively correlated with their use of achievement words with their children, and the number of AR CAG trinucleotide repeats was inversely correlated with their use of anger and reward words with their children. T levels were positively correlated with sexual language and with use of swear words in the presence of their partner, but not in the presence of co-workers or children.

CONCLUSIONS

Together, these results suggest that T may influence social behavior by increasing the frequency of words related to aggression, sexuality, and status, and that it may alter the quality of interactions with an intimate partner by amplifying emotions via swearing.

Longer trinucleotide repeats of androgen receptor are associated with higher testosterone and low oxytocin levels in diabetic premature ejaculatory dysfunction patients

Background

Despite its worldwide high occurrence, the obscurity regarding the description, epidemiology and management of premature ejaculation remains provocative. It is well established that male premature ejaculatory dysfunction is an increasing problem due to spontaneous ejaculation across a variety of general and clinical subjects. The main goal of this study was to determine the relationships between trinucleotide repeats of the androgen receptor (AR), sex steroids, and pituitary hormones with sexual function in men with type 2 diabetes mellitus (DM) and reported with acquired premature ejaculation (PE).

Methods

A total of 150 normal and 250 PE + DM subjects were enrolled in this study. Each subject was invited to fill out an elaborative questionnaire to acquire precise selective information regarding BMI, duration of PE + DM, self-reported Intra-Vaginal Ejaculatory Latency Time (IELT), sexual and mental health status by using the premature ejaculation diagnostic tool (PEDT) and Beck Depression Inventory-II (BDI-II). Pearson's correlation analysis was used to analyze the relationship between clinical, hormonal, and genetic variables. Ward's minimum variance cluster analysis and principal component analysis were used for evaluation of dependence between genetic, clinical, and demographic parameters.

Results

The patients who have the lowest number of (≤21) (CAG)n repeats have higher serum oxytocin levels (114.2 pg/ml; n = 54, 43.2%) than the controls (69.18 pg/ml; n = 22, 17.6%) and the patients with the highest (≥26) number of (CAG)n repeats (62.9 pg/ml; n = 108, 43.2%).On the other hand, patients who have the highest numbers of (CAG)n repeats (≥26) have higher serum testosterone (6.1 ng/ml; n = 108, 43.2% of cohort) lower prolactin (3.01 ng/ml; n = 108, 43.2% of cohort) levels than the controls and patients with the lowest numbers (≤21) of (CAG)n repeats and their TSH (1.53 mIU/L, P < 0.05) levels are lower than those of controls. In the Pearson correlation model, self-estimated IELT demonstrated significantly negative correlation with both (CAG)n and (GCC)n repeats (r = - 0.16, p = 0.0001; r = - 0.19, p = 0.0001) respectively. These repeats have positive correlation with PEDT (r = 0.28, p = 0.0001: r = 0.24, p = 0.0001, whole model) and inversely correlated with BDI-II (r = - 0.25, p = 0.0001).

Conclusion

This study indicates that androgen receptor polymorphism modulates the endocrine effect on ejaculatory reflex and depends strongly on its "cofactors". Moreover, our results also confirmed an association between long tri-nucleotide repeats of androgen receptor, sex steroids, pituitary, and thyroid hormones in relation to  acquired premature ejaculatory dysfunction in diabetic patients. However, endocrine regulation of PE reflex is a complex phenomenon that requires further investigation.

Functional significance of men's testosterone reactivity to social stimuli

Rapid testosterone fluctuations in response to social stimuli are observed across a wide range of species, and the highly conserved nature of these fluctuations suggests an adaptive function. This paper reviews the current literature on testosterone reactivity, primarily in human males, and illustrates how life-history theory provides an adequate theoretical framework to interpret findings. The review is structured around supporting evidence suggesting that situations implicated in mating effort either directly (e.g., interactions with a mate) or indirectly (e.g., intrasexual competition) are generally associated with a brief elevation of testosterone, while situations implicated in parenting effort (e.g., nurturant interactions with offspring) are generally associated with a decline in testosterone. Further, we discuss how these fluctuations in testosterone have been linked to future behaviors, and how situational, motivational, and physiological variables moderate the interplay between social stimuli, testosterone reactivity, and behavior. Supporting the notion that testosterone can play a causal role in modulating behavior in response to social stimuli, we also summarize recent single administration studies examining the effects of testosterone on physiology, neurobiology, and behavior. A conceptual model provides links between supported findings, and hypothesized pathways requiring future testing.

High paternal testosterone may protect against postpartum depressive symptoms in fathers, but confer risk to mothers and children

Following the birth of an infant, decreases in testosterone and increases in depressive symptoms have been observed in fathers. Paternal testosterone may reflect fathers' investment in pair-bonding and paternal caregiving and, as such, may be associated with maternal and familial well-being. This study tests associations between paternal testosterone, paternal and maternal postpartum depressive symptoms, and subsequent family functioning. Within 149 couples, fathers provided testosterone samples when infants were approximately nine months old and both parents reported on postpartum depressive symptoms at two, nine, and 15months postpartum. Fathers with lower aggregate testosterone reported more depressive symptoms at two and nine months postpartum. Mothers whose partners had higher evening testosterone reported more depressive symptoms at nine and 15months postpartum. Maternal relationship satisfaction mediated this effect, such that mothers with higher testosterone partners reported more relationship dissatisfaction, which in turn predicted more maternal depressive symptoms. Higher paternal testosterone and paternal depressive symptoms at nine months postpartum each independently predicted greater fathering stress at 15months postpartum. Higher paternal testosterone also predicted more mother-reported intimate partner aggression at 15months postpartum. In addition to linear relationships between testosterone and depression, curvilinear relationships emerged such that fathers with both low and high testosterone at nine months postpartum reported more subsequent (15-month) depressive symptoms and fathering stress. In conclusion, whereas higher paternal testosterone may protect against paternal depression, it contributed to maternal distress and suboptimal family outcomes in our sample. Interventions that supplement or alter men's testosterone may have unintended consequences for family well-being.