Ovarian function in Samoan women shows stronger association with signals of energy metabolism than fat reserves

Endocrinological effects of social exclusion and inclusion: Experimental evidence for adaptive regulation of female fecundity

When current conditions are probabilistically less suitable for successful reproduction than future conditions, females may prevent or delay reproduction until conditions improve. Throughout human evolution, social support was likely crucial to female reproductive success. Women may thus have evolved fertility regulation systems sensitive to cues from the social environment. However, current understanding of how psychological phenomena might affect female ovarian function is limited. In this study, we examined whether cues of reduced social support-social ostracism-impact women's hormone production. Following an in-lab group bonding task, women were randomly assigned to a social exclusion (n = 88) or social inclusion (n = 81) condition. After social exclusion, women with low background levels of social support experienced a decrease in estradiol relative to progesterone. In contrast, socially-included women with low background social support experienced an increase in estradiol relative to progesterone. Hormonal changes in both conditions occurred specifically when women were in their mid-to-late follicular phase, when baseline estradiol is high and progesterone is low. Follow-up analyses revealed that these changes were primarily driven by changes in progesterone, consistent with existing evidence for disruption of ovarian function following adrenal release of follicular-phase progesterone. Results offer support for a potential mechanism by which fecundity could respond adaptively to the loss or lack of social support.

Organizational and activational androgens, lemur social play, and the ontogeny of female dominance

The role of androgens in shaping "masculine" traits in males is a core focus in behavioral endocrinology, but relatively little is known about an androgenic role in female aggression and social dominance. In mammalian models of female dominance, including the ring-tailed lemur (Lemur catta), links to androgens in adulthood are variable. We studied the development of ring-tailed lemurs to address the behavioral basis and ontogenetic mechanisms of female dominance. We measured behavior and serum androgen concentrations in 24 lemurs (8 males, 16 females) from infancy to early adulthood, and assessed their 'prenatal' androgen milieu using serum samples obtained from their mothers during gestation. Because logistical constraints limited the frequency of infant blood sampling, we accounted for asynchrony between behavioral and postnatal hormone measurements via imputation procedures. Imputation was unnecessary for prenatal hormone measurements. The typical sex difference in androgen concentrations in young lemurs was consistent with adult conspecifics and most other mammals; however, we found no significant sex differences in rough-and-tumble play. Female (but not male) aggression increased beginning at approximately 15 months, coincident with female puberty. In our analyses relating sexually differentiated behavior to androgens, we found no relationship with activational hormones, but several significant relationships with organizational hormones. Notably, associations of prenatal androstenedione and testosterone with behavior were differentiated, both by offspring sex and by type of behavior within offspring sexes. We discuss the importance of considering (1) missing data in behavioral endocrinology research, and (2) organizational androgens other than testosterone in studies of female dominance.

Reproductive health, obesity, and cardiometabolic risk factors among Samoan women

OBJECTIVES

Obesity leads to deleterious effects on not only cardiovascular health but also on the reproductive health of women. We estimate the prevalence of menstrual irregularity and of polycystic ovarian syndrome (PCOS) in Samoan women, among whom obesity prevalence is extremely high. We explore the association of these reproductive health conditions with adiposity, cardiometabolic risk factors, and androgen levels.

METHODS

A cross-sectional sample of Samoan women 25-39 years of age (n = 470) from a larger population-based genome-wide association study of adiposity and cardiometabolic disease was assessed for the prevalence of oligomenorrhea/amenorrhea (OM/AM) using a self-reported questionnaire. Serum androgens and anti-Müllerian hormone levels were assayed to determine hyperandrogenemia and presence of polycystic ovaries (PCO), respectively, using criterion values. PCOS was classified using NIH guidelines of having at least two of the three conditions: menstrual irregularity, hyperandrogenism, and PCO. We contrasted socio-demographic, reproductive health, and cardiometabolic risk factors between those with and without OM/AM and similarly for PCOS.

RESULTS

The prevalence of OM/AM was 7.4% (95% CI: 5.1, 9.8), and women with OM/AM had significantly higher central adiposity. PCOS was estimated at 6.8% (95% CI: 4.5, 9.1), and those with PCOS were younger but had higher overall and central adiposity measures, higher triglycerides, and higher prevalence of insulin resistance than women without PCOS.

CONCLUSIONS

The prevalence of menstrual irregularity and PCOS are less than hypothesized given the high levels of adiposity in this population. Nevertheless, Samoan women with menstrual irregularity and other features of PCOS have significantly poorer metabolic health.

Endocrinology, energetics, and human life history: A synthetic model

Human life histories are shaped by the allocation of metabolic energy to competing physiological domains. A model framework of the pathways of energy allocation is described and hormonal regulators of allocation along the pathways of the framework are discussed in the light of evidence from field studies of the endocrinology of human energetics. The framework is then used to generate simple models of two important life history transitions in humans, puberty and the postpartum return to full fecundity in females. The results of the models correspond very closely to observations made in the field.

CYP17 genotype modifies the impact of anthropometric variation on salivary estradiol in healthy women

Several studies demonstrate that human ovarian function is responsive to the energetic environment, which has led to the development of theoretical models that explain this phenomenon. Although many genes are involved in ovarian hormone production, the possibility that genetic polymorphism may affect ovarian response to energetic conditions has not been considered. Cytochrome P450c17α is an enzyme that produces androgen precursors used to make estrogens during ovarian steroidogenesis, and is encoded by the CYP17 gene. A functionally significant variant within the promoter region of CYP17 has been linked to variation in steroid production, and some evidence suggests that this polymorphism could alter transcription of CYP17 in an insulin-dependent manner. We tested the hypothesis that the CYP17 variant affected the relationship between anthropometric measurements and salivary estradiol in healthy women in the United States (n = 28). PCR-RLFP analysis was used to genotype women for the genetic variant, and estradiol was assayed from saliva by EIA. Moderated regression analysis of these preliminary data revealed a significant interaction between waist-to-hip ratio and CYP17 genotype (P = 0.004). Our study provides evidence that gene-environment interactions should be considered in future adaptive models for human ovarian function. Moreover, our results stand to illuminate possible associations between this genetic variant and reproductive disease.