Estrogen in the Limbic System

The pathophysiology of estrogen in perinatal depression: conceptual update

PURPOSE

Estrogen levels fall sharply after parturition and have long been considered an etiologic contributor to postpartum depression (PPD); however, no differences have been reported in plasma hormone concentrations in people who develop PPD. We examine the question: What is the current view of estrogen and the neurophysiologic processes it impacts in the development and treatment of PPD?

METHODS

A literature review of the role of estrogen on candidate hormonal and epigenetic systems in the peripartum period was performed, including landmark historical studies and recent publications on estrogen-related research. The authors reviewed these papers and participated in reaching consensus on a conceptual framework of estrogen activity within the complexity of pregnancy physiology to examine its potential role for driving novel interventions.

RESULTS

Estrogen fluctuations must be conceptualized in the context of multiple dramatic and interacting changes inherent in pregnancy and after birth, including progesterone, corticosteroids, inflammation, circadian biology and psychosocial challenges. Individuals who develop PPD have increased sensitivity to epigenetic alteration at estrogen-responsive genes, and these changes are highly predictive of PPD. An effective estrogen-based treatment for PPD has yet to be found, but interventions focused on associated inflammation and circadian rhythms are promising.

CONCLUSIONS

Our understanding of the biological basis of PPD, one of the most common morbidities of the perinatal period, is expanding beyond changes in gynecologic hormone concentrations to include their impact on other systems. This growing understanding of the many processes influencing PPD will allow for the development of novel prevention and treatment strategies.

DNA Methylation in Autism Spectrum Disorders: Biomarker or Pharmacological Target?

Autism spectrum disorder (ASD) is a group of heterogeneous neurodevelopmental disabilities with persistent impairments in cognition, communication, and social behavior. Although environmental factors play a role in ASD etiopathogenesis, a growing body of evidence indicates that ASD is highly inherited. In the last two decades, the dramatic rise in the prevalence of ASD has interested researchers to explore the etiologic role of epigenetic marking and incredibly abnormal DNA methylation. This review aimed to explain the current understanding of the association between changes in DNA methylation signatures and ASD in patients or animal models. We reviewed studies reporting alterations in DNA methylation at specific genes as well as epigenome-wide association studies (EWASs). Finally, we hypothesized that specific changes in DNA methylation patterns could be considered a potential biomarker for ASD diagnosis and prognosis and even a target for pharmacological intervention.

Associations of schizophrenia with the activities of the HPA and HPG axes and their interactions characterized by hair-based biomarkers

BACKGROUND

Past studies on schizophrenia (SCZ) and the stress-sensitive neuroendocrine systems have mostly focused on a single system and traditionally utilized acute biomarkers (e.g., biomarkers from blood, urine and saliva) that poorly match the chronic course of schizophrenia in time span. Using eight biomarkers in hair, this study aimed to explore the functional characteristics of SCZ patients in the hypothalamic-pituitary-adrenocortical (HPA) and hypothalamic-pituitary-gonadal (HPG) axes and the interaction between the two axes.

METHODS

Hair samples were taken from 137 SCZ patients and 73 controls. The SCZ patients were diagnosed by their attending physician according to the Diagnostic and Statistical Manual of Mental Disorders IV and were clinically stable after treatment. Gender, age, BMI, frequency of hair washing, marital status, education level, family history of mental illness and clozapine dosage were concurrently collected as covariates. The 10-item perceived stress scale (PSS-10) and the social readjustment rating scale were used to assess chronic stress status in SCZ patients. Eight hair biomarkers, cortisol, cortisone, dehydroepiandrosterone (DHEA), testosterone, progesterone, cortisol/cortisone, cortisol/DHEA and cortisol/testosterone, were measured by high performance liquid chromatography tandem mass spectrometer. Among them, cortisol, cortisone, DHEA and cortisol/DHEA reflected the functional activity of the HPA axis, and testosterone and progesterone reflected the functional activity of the HPG axis, and cortisol/cortisone reflected the activity of 11β-hydroxysteroid dehydrogenase types 2 (11β-HSD 2), and cortisol/testosterone reflected the HPA-HPG interaction.

RESULTS

SCZ patients showed significantly higher cortisone and cortisol/testosterone than controls (p<0.001, η²p=0.180 and p=0.015, η²p=0.031), lower testosterone (p=0.009, η²p=0.034), progesterone (p<0.001, η²p=0.069) and cortisol/cortisone (p=0.001, η²p=0.054). There were significant intergroup differences in male and female progesterone (p=0.003, η²p=0.088 and p=0.030, η²p=0.049) and female testosterone (p=0.028, η²p=0.051). In SCZ patients, cortisol, cortisol/cortisone, cortisol/DHEA and cortisol/testosterone were positively associated with PSS-10 score (ps<0.05, 0.212

CONCLUSION

The function of the HPA and HPG axes, the activity of 11β-HSD 2 and the HPA-HPG interaction were abnormal in SCZ patients. The abnormality of neuroendocrine systems was associated with chronic stress status in SCZ patients. This study provided evidence for abnormalities in the neuroendocrine systems in SCZ patients.

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Key Words

• 11β-HSD 2
• HPA axis
• HPG axis
• Hair biomarkers
• Schizophrenia

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MESH Headings

• Humans
• Female
• Male
• Hypothalamo-Hypophyseal System/metabolism
• Schizophrenia/metabolism
• Pituitary-Adrenal System/metabolism
• Pituitary-Adrenal System/physiopathology
• Hair/chemistry
• Hair/metabolism
• Biomarkers/metabolism
• Adult
• Hydrocortisone/metabolism
• Hydrocortisone/analysis
• Cortisone/metabolism
• Cortisone/analysis
• Testosterone/metabolism
• Testosterone/analysis
• Dehydroepiandrosterone/metabolism
• Dehydroepiandrosterone/analysis
• Stress, Psychological/metabolism
• Middle Aged
• Progesterone/metabolism
• Progesterone/analysis
• Case-Control Studies

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Affiliation(s)

Deyi Qi Department of Brain and Learning Science, School of Biological Science & Medical Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Child Development and Learning Science (Southeast University), Ministry of Education, Nanjing 211189, China; Institute of Child Development and Education, Southeast University, Nanjing 211189, China
Weiliang Wang School of Nursing, Harbin Medical University, Harbin 163319, China.
Liuxi Chu Department of Brain and Learning Science, School of Biological Science & Medical Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Child Development and Learning Science (Southeast University), Ministry of Education, Nanjing 211189, China; Institute of Child Development and Education, Southeast University, Nanjing 211189, China
Yan Wu Department of Brain and Learning Science, School of Biological Science & Medical Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Child Development and Learning Science (Southeast University), Ministry of Education, Nanjing 211189, China; Institute of Child Development and Education, Southeast University, Nanjing 211189, China
Wei Wang Department of Brain and Learning Science, School of Biological Science & Medical Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Child Development and Learning Science (Southeast University), Ministry of Education, Nanjing 211189, China; Institute of Child Development and Education, Southeast University, Nanjing 211189, China
Minhui Zhu Department of Brain and Learning Science, School of Biological Science & Medical Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Child Development and Learning Science (Southeast University), Ministry of Education, Nanjing 211189, China; Institute of Child Development and Education, Southeast University, Nanjing 211189, China
Lin Yuan Department of Brain and Learning Science, School of Biological Science & Medical Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Child Development and Learning Science (Southeast University), Ministry of Education, Nanjing 211189, China; Institute of Child Development and Education, Southeast University, Nanjing 211189, China
Wei Gao Institute of Child Development and Education, Southeast University, Nanjing 211189, China; School of Psychology, Nanjing Normal University, Nanjing 210024, China
Huihua Deng Department of Brain and Learning Science, School of Biological Science & Medical Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Child Development and Learning Science (Southeast University), Ministry of Education, Nanjing 211189, China; Institute of Child Development and Education, Southeast University, Nanjing 211189, China.

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Sex as a Determinant of Age-Related Changes in the Brain

The notion of notable anatomical, biochemical, and behavioral distinctions within male and female brains has been a contentious topic of interest within the scientific community over several decades. Advancements in neuroimaging and molecular biological techniques have increasingly elucidated common mechanisms characterizing brain aging while also revealing disparities between sexes in these processes. Variations in cognitive functions; susceptibility to and progression of neurodegenerative conditions, notably Alzheimer's and Parkinson's diseases; and notable disparities in life expectancy between sexes, underscore the significance of evaluating aging within the framework of gender differences. This comprehensive review surveys contemporary literature on the restructuring of brain structures and fundamental processes unfolding in the aging brain at cellular and molecular levels, with a focus on gender distinctions. Additionally, the review delves into age-related cognitive alterations, exploring factors influencing the acceleration or deceleration of aging, with particular attention to estrogen's hormonal support of the central nervous system.

The Role of Piromelatine on Peripheral and Hippocampal Insulin Resistance in Rat Offspring Exposed to Chronic Maternal Stress

Prenatal stress (PNS), which alters the hypothalamic-pituitary-adrenal axis function in the offspring, predisposes to insulin resistance (IR) in later life and is associated with numerous disorders, including cognitive and memory impairments. At present, our main goal is to assess the effects of chronic piromelatine (Pir) administration, a melatonin analogue, on PNS-provoked IR in the periphery and the hippocampus in male and female offspring. Pregnant Sprague-Dawley rats were exposed to chronic stress (one short-term stressor on a daily basis and one long-term stressor on a nightly basis) from the first gestation week until birth. Vehicle or Pir 20 mg/kg were administered intraperitoneally for 21 days. Plasma glucose, serum insulin levels, and the homeostasis model assessment of insulin resistance (HOMA-IR) were determined as markers of peripheral IR. For the hippocampal IR assessment, insulin receptors (IRs) and glucose transporter 4 (GLUT4) were examined. Prenatally stressed offspring of both sexes indicated enhanced plasma glucose and serum insulin concentrations, increased HOMA-IR, and decreased hippocampal GLUT4 only in male rats. The PNS-induced changes were corrected by chronic treatment with Pir. The present results suggest that the melatoninergic compound Pir exerts beneficial effects on altered glucose/insulin homeostasis in PNS-exposed offspring.

Effects of dietary soy content on cerebral artery function and behavior in ovariectomized female mice

As females age, they transition through menopause, experiencing a decrease in estrogen and an increase in cardiovascular and neurodegenerative disease risk. Most standard rodent chows contain phytoestrogen-rich soybean meal, which can mimic the effects of estrogen. Understanding the impact of this soybean meal on vascular outcomes is crucial to proper experimental design. Thus, this study aimed to compare the effects of standard and soy-free chows on cerebral artery endothelial function and cognitive function in ovariectomized mice. Young female C57Bl/6J mice (n = 43; ∼6 mo) were randomly assigned to three groups: sham, ovariectomy (OVX), or ovariectomy on a diet containing soy (OVX + Soy). In posterior cerebral arteries, the OVX mice had a 27% lower maximal response to insulin compared with the sham mice. The OVX + Soy mice had a 27% greater maximal vasodilation to insulin compared with the OVX mice and there were no differences in vasodilation between the OVX + Soy and sham groups. The group differences in vasodilation were mediated by differences in nitric oxide bioavailability. The OVX + Soy mice also had greater insulin receptor gene expression in cerebral arteries compared with the OVX mice. However, no differences in aortic or cerebral artery stiffness were observed between groups. Interestingly, the OVX + Soy group scored better on nesting behavior compared with both sham and OVX groups. In summary, we found that ovariectomy impairs insulin-mediated vasodilation in cerebral arteries, but a diet containing soy mitigates these effects. These findings highlight the importance of considering dietary soy when performing vascular and behavioral tests in mice, particularly in females.NEW & NOTEWORTHY To properly design experiments, we must consider how variables like diet impact our outcomes, particularly the effects of soy on females. We found that cerebral artery vasodilation in response to insulin was impaired in ovariectomized female mice compared with intact shams. However, ovariectomized mice fed a soy diet had a preserved cerebral artery insulin-mediated vasodilation. These results highlight that the effects of diet on vascular function may explain inconsistencies found between studies.

Attention-deficit/hyperactivity disorder and the menstrual cycle: Theory and evidence

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that exhibits striking sex differences in symptoms, prevalence, and associated problems across development. Etiological factors and mechanisms underlying these sex differences remain one of the most understudied aspects of this disorder. The current paper seeks to provide a novel theoretical framework for understanding this phenomenon by reviewing evidence that females with ADHD may experience a "double whammy" of organizational and activational pubertal hormonal effects. We propose a novel theory of activational effects of cyclical circulating ovarian hormones on ADHD with increasing risk at times of rapid declines in estrogen. These declines may decrease executive function and trait control at two points of the cycle characterized by biphasic affective risk: (1) increases in approach/risk-taking behaviors at mid-cycle (periovulatory) and (2) increases in avoidance/negative affect perimenstrually. Low estrogen and control may then interact with increases in positive and negative affect, respectively, to increase hyperactivity-impulsivity symptoms post-ovulation and inattention symptoms perimenstrually. These interactions may be exacerbated by organizational pubertal effects on relatively overdeveloped limbic circuitry and adolescent-specific social pressures magnified in females with ADHD.

Machine learning in the prediction of postpartum depression: A review

BACKGROUND

Current screening options in the setting of postpartum depression (PPD) are firmly rooted in self-report symptom-based tools. The implementation of the modern machine learning (ML) approaches might, in this context, represent a way to refine patient screening by precisely identifying possible PPD predictors and, subsequently, a population at risk of developing the disease, in an effort to lower its morbidity, mortality and its economic burden.

METHODS

We performed a bibliographic search on PubMed and Embase looking for studies aimed at the identification of PPD predictors using ML techniques.

RESULTS

Among the 482 articles retrieved, 11 met the inclusion criteria. The most used algorithm was the support vector machine. Notably, all studies reached an area under the curve above 0.7, ultimately suggesting that the prediction of PPD could be feasible. Variables obtained from sociodemographic and clinical aspects (psychiatric and gynecological factors) seem to be the most reliable. Only three studies employed biological variables, in the form of blood, genetic and epigenetic predictors, while no study employed imaging techniques.

LIMITATIONS

The literature on PPD prediction via ML techniques is currently scarce, with most studies employing different variables selection and ML algorithms, ultimately reducing the generalizability of the results.

CONCLUSIONS

The identification of a population at risk of developing PPD might be feasible with current technology and clinical knowledge. Further studies are necessary to clarify how such an approach could be implemented into clinical practice.

Grey matter correlates of affective and somatic symptoms of premenstrual dysphoric disorder

Ovarian hormones fluctuations across the menstrual cycle are experienced by about 58% of women in their fertile age. Maladaptive brain sensitivity to these changes likely leads to the severe psychological, cognitive, and physical symptoms repeatedly experienced by women with Premenstrual Dysphoric Disorder (PMDD) during the late luteal phase of the menstrual cycle. However, the neuroanatomical correlates of these symptoms are unknown. The relationship between grey matter structure and PMDD symptom severity was delineated using structural magnetic resonance imaging during the late luteal phase of fifty-one women diagnosed with PMDD, combined with Voxel- and Surface-Based Morphometry, as well as subcortical volumetric analyses. A negative correlation was found between depression-related symptoms and grey matter volume of the bilateral amygdala. Moreover, the severity of affective and somatic PMDD symptoms correlated with cortical thickness, gyrification, sulcal depth, and complexity metrics, particularly in the prefrontal, cingulate, and parahippocampal gyri. The present findings provide the first evidence of grey matter morphological characteristics associated with PMDD symptomatology in brain regions expressing ovarian hormone receptors and of relevance to cognitive-affective functions, thus potentially having important implications for understanding how structural brain characteristics relate to PMDD symptomatology.

Exposure to environmental chemicals and perinatal psychopathology

Women are nearly twice as likely to develop mood disorders compared with men, and incidence is greatest during reproductive transitions, including pregnancy and postpartum. Because these periods are characterized by dramatic hormonal and physiologic changes, there is heightened susceptibility to external factors, such as exposure to environmental toxicants, which may play a role in maternal psychopathology. The purpose of this scoping review was to provide an overview of studies conducted in humans and animal models on the effects of nonoccupational exposure to environmental chemicals on maternal psychopathology during the perinatal period. The largest number of studies examined exposure to environmental tobacco smoke and antenatal depression and showed consistently positive findings, although more prospective studies using biomarkers for exposure assessment are needed. The few studies examining persistent organic pollutants such as polybrominated diphenyl ethers and perinatal depression were consistent in showing associations with increased depressive symptoms. Results were mixed for exposure to heavy metals and non-persistent chemicals, but a strong literature in animal models supported an association between bisphenols and phthalates and reduced maternal behavior and care of pups after parturition. Biological mechanisms may include endocrine disruption, neurotransmitter system impairment, alterations in gene expression, and immune activation and inflammation. Additional longitudinal studies that include biospecimen collection are essential to furthering the understanding of how environmental toxicants during pregnancy may affect perinatal psychopathology and the underlying mechanisms of action. Future work should also leverage the parallels between animal and human maternal behavior, thereby highlighting the opportunity for multidisciplinary work in this avenue.

Estrogen receptors-β and serotonin mediate the antidepressant-like effect of an aqueous extract of pomegranate in ovariectomized rats

Pomegranate (Punica granatum) fruit is of particular interest because of its high nutritional value and therapeutic actions. Recently, we showed that an aqueous extract of pomegranate (AE-PG) given by oral route induced antidepressant-like actions mediated by estrogen receptors (ERs) suggesting its potential to function as an alternative to estrogen therapy replacement in menopause-related depression treatment. Orally administered AE-PG allows the biotransformation of ellagitannins into active estrogenic compounds through the intestinal microbiota. However, it is necessary to know if compounds that do not need to be biotransformed by the intestinal microbiota are involved in the antidepressant-like effects. Therefore, the first aim of this study was to determine if AE-PG produces an antidepressant-like effect when administered intraperitoneally. Also, to determine the participation of specific ER-subtypes (α or β) and to analyze the role of the serotonergic system. Young female Wistar rats were ovariectomized as a surgical model of menopause. The intraperitoneal administration of AE-PG (1 mg/kg; i. p.) was evaluated in the forced swimming test and open field tests. Also, the ERα antagonist (TPBM; 50 μg/rat; s. c.) or the ERβ antagonist (PHTPP; 25 μg/rat; s. c.) were administered with AE-PG to analyze the participation of the specific ERs. Finally, the effect of the serotonin neurotoxin 5,7-DHT (200 μg/rat; i. c.v.) on the antidepressant-like effect of the AE-PG was studied in independent experimental groups. RESULTS: showed that AE-PG administered by intraperitoneal route induced antidepressant-like effects. This result suggests that gut microbiota biotransformation is not necessary to exert its actions. The mechanism of action involves the activation of the ERβ and the serotonergic system. Altogether, this information contributes to the elucidation of the antidepressant action of the pomegranate fruit, which could be further considered as an alternative treatment for depression during menopause.

Insight Analysis of Promiscuous Estrogen Receptor α-Ligand Binding by a Novel Machine Learning Scheme

Estrogen receptor α (ERα) plays a significant role in occurrence of breast cancer and may cause various adverse side-effects when ERα is an off-target protein. A theoretical model was derived to predict the binding affinity of ERα using the pharmacophore ensemble/support vector machine (PhE/SVM) scheme to consider the promiscuous characteristic of ERα. The estimations by PhE/SVM were discovered to be in good agreement with the observed values for those training molecules ( n = 31, r² = 0.80, q_CV² = 0.77, RMSE = 0.57, s = 0.58), test molecules ( n = 179, q² = 0.91-0.96, RMSE = 0.33, s = 0.26) and outliers ( n = 15, q² = 0.80-0.86, RMSE = 0.56, s = 0.49). When subjected to various statistical validations, the PhE/SVM model consistently fulfilled the strictest criteria. A mock test also asserted its predictivity. When compared with crystal structures, the calculated results are consistent with the reported ERα-ligand co-complex structure, and the plasticity nature of ERα is also disclosed. Consequently, this precise, fast, and robust model can be adopted to predict ERα-ligand binding affinities and to design safer non-ERα-targeted pharmaceuticals in the process of drug discovery and development.

Analysis of estrogen receptor β gene methylation in autistic males in a Chinese Han population

Autism spectrum disorder (ASD) is a neurodevelopment disorder with abnormalities of social interaction, communication and repetitive behaviors. The higher prevalence of ASD in men implies a potential relationship between sex hormones and ASD etiology. The ESR2 gene encodes estrogen receptor beta (ESR2) and plays an important role during brain development. A relationship between ESR2 and ASD has been suggested by studies on single nucleotide polymorphisms and mRNA and protein expression levels in ASD patients. Here, we explored the possible epigenetic regulation of the ESR2 gene in autism. We collected genomic DNA from the peripheral blood of Chinese Han males with autism and age-matched normal males and measured DNA methylation of CpG islands in the ESR2 gene, which consisted of 41 CpG sites among the proximal promoter region and an untranslated exon, by bisulfite sequencing. We also investigated a relationship between DNA methylation and phenotypic features of autism, as assessed by the Children Autism Rating Scale. We found little overall difference in the DNA methylation of the ESR2 5'-flanking region in individuals with autism compared with normal individuals. However, detailed analyses revealed that eight specific CpG sites were hypermethylated in autistic individuals and that four specific CpG sites were positively associated with the severity of autistic symptoms. Our study indicates that the epigenetic dysregulation of ESR2 may govern the development of autism.

Hippocampal serotonin-2A receptor-immunoreactive neurons density increases after testosterone therapy in the gonadectomized male mice

The change of steroid levels may also exert different modulatory effects on the number and class of serotonin receptors present in the plasma membrane. The effects of chronic treatment of testosterone for anxiety were examined and expression of 5-HT_2A serotonergic receptor, neuron, astrocyte, and dark neuron density in the hippocampus of gonadectomized male mice was determined. Thirty-six adult male NMRI mice were randomly divided into six groups: intact-no testosterone treatment (No T), gonadectomy (GDX)-No T, GDX-Vehicle, GDX-6.25 mg/kg testosterone (T), GDX-12.5 mg/kg T, and GDX-25 mg/kg T. Anxiety-related behavior was evaluated using elevated plus maze apparatus. The animals were anesthetized after 48 hours after behavioral testing, and decapitated and micron slices were prepared for immunohistochemical as well as histopathological assessment. Subcutaneous injection of testosterone (25 mg/kg) may induce anxiogenic-like behavior in male mice. In addition, immunohistochemical data reveal reduced expression of 5-HT_2A serotonergic receptor after gonadectomy in all areas of the hippocampus. However, treatment with testosterone could increase the mean number of dark neurons as well as immunoreactive neurons in CA1 and CA3 area, dose dependently. The density of 5-HT_2A receptor-immunoreactive neurons may play a crucial role in the induction of anxiety like behavior. As reduction in such receptor expression have shown to significantly enhance anxiety behaviors. However, replacement of testosterone dose dependently enhances the number of 5-HT_2A receptor-immunoreactive neurons and interestingly also reduced anxiety like behaviors.

Tetratricopeptide repeat domain 9A modulates anxiety-like behavior in female mice

Tetratricopeptide repeat domain 9A (TTC9A) expression is abundantly expressed in the brain. Previous studies in TTC9A knockout (TTC9A^-/-) mice have indicated that TTC9A negatively regulates the action of estrogen. In this study we investigated the role of TTC9A on anxiety-like behavior through its functional interaction with estrogen using the TTC9A^-/- mice model. A battery of tests on anxiety-related behaviors was conducted. Our results demonstrated that TTC9A^-/- mice exhibited an increase in anxiety-like behaviors compared to the wild type TTC9A^+/+ mice. This difference was abolished after ovariectomy, and administration of 17-β-estradiol benzoate (EB) restored this escalated anxiety-like behavior in TTC9A^-/- mice. Since serotonin is well-known to be the key neuromodulator involved in anxiety behaviors, the mRNA levels of tryptophan hydroxylase (TPH) 1, TPH2 (both are involved in serotonin synthesis), and serotonin transporter (5-HTT) were measured in the ventromedial prefrontal cortex (vmPFC) and dorsal raphe nucleus (DRN). Interestingly, the heightened anxiety in TTC9A^-/- mice under EB influence is consistent with a greater induction of TPH 2, and 5-HTT by EB in DRN that play key roles in emotion regulation. In conclusion, our data indicate that TTC9A modulates the anxiety-related behaviors through modulation of estrogen action on the serotonergic system in the DRN.

Cooperation of Genomic and Rapid Nongenomic Actions of Estrogens in Synaptic Plasticity

Neuroplasticity refers to the changes in the molecular and cellular processes of neural circuits that occur in response to environmental experiences. Clinical and experimental studies have increasingly shown that estrogens participate in the neuroplasticity involved in cognition, behavior, and memory. It is generally accepted that estrogens exert their effects through genomic actions that occur over a period of hours to days. However, emerging evidence indicates that estrogens also rapidly influence the neural circuitry through nongenomic actions. In this review, we provide an overview of the genomic and nongenomic actions of estrogens and discuss how these actions may cooperate in synaptic plasticity. We then summarize the role of epigenetic modifications, synaptic protein synthesis, and posttranslational modifications, and the splice variants of estrogen receptors in the complicated network of estrogens. The combination of genomic and nongenomic mechanisms endows estrogens with considerable diversity in modulating neural functions including synaptic plasticity.

Replication of Epigenetic Postpartum Depression Biomarkers and Variation with Hormone Levels

DNA methylation variation at HP1BP3 and TTC9B is modified by estrogen exposure in the rodent hippocampus and was previously shown to be prospectively predictive of postpartum depression (PPD) when modeled in antenatal blood. The objective of this study was to replicate the predictive efficacy of the previously established model in women with and without a previous psychiatric diagnosis and to understand the effects of changing hormone levels on PPD biomarker loci. Using a statistical model trained on DNA methylation data from N=51 high-risk women, we prospectively predicted PPD status in an independent N=51 women using first trimester antenatal gene expression levels of HP1BP3 and TTC9B, with an area under the receiver operator characteristic curve (AUC) of 0.81 (95% CI: 0.69-0.92, p<5 × 10(-4)). Modeling DNA methylation of these genes in N=240 women without a previous psychiatric diagnosis resulted in a cross-sectional prediction of PPD status with an AUC of 0.81 (95% CI: 0.68-0.93, p=0.01). TTC9B and HP1BP3 DNA methylation at early antenatal time points showed moderate evidence for association to the change in estradiol and allopregnanolone over the course of pregnancy, suggesting that epigenetic variation at these loci may be important for mediating hormonal sensitivity. In addition both loci showed PPD-specific trajectories with age, possibly mediated by age-associated hormonal changes. The data add to the growing body of evidence suggesting that PPD is mediated by differential gene expression and epigenetic sensitivity to pregnancy hormones and that modeling proxies of this sensitivity enable accurate prediction of PPD.

Effect of curcumin on serum brain-derived neurotrophic factor levels in women with premenstrual syndrome: A randomized, double-blind, placebo-controlled trial

Premenstrual syndrome (PMS) is a variety of physical, mental, and behavioral symptoms that start during the late luteal phase of the menstrual cycle, and the symptoms disappear after the onset of menses. Serum brain-derived neurotrophic factor (BDNF) levels during luteal phase in women associated with PMS have more alterations than women not suffering from PMS. In this regard, altered luteal BDNF levels in women with PMS might play a role in a set of psychological and somatic symptoms of the PMS. Studies of last decade revealed neuroprotective effects of curcumin and its ability to increase BDNF levels. In the present study, we evaluated the effect of curcumin on serum BDNF level and PMS symptoms severity in women with PMS. Present study is a Randomized, Double-Blinded, Placebo-Controlled Clinical Trial. Curcumin treatment was given for three successive menstrual cycles and each cycle ran 10 days. After having identified persons with PMS, participants were randomly allocated into placebo (n=35) and curcumin (n=35) groups. Each sample in placebo and curcumin groups received two capsules daily for seven days before menstruation and for three days after menstruation for three successive menstrual cycles. Participants noted the severity of the symptoms mentioned in the daily record questionnaire. Self-report was used to determine menstrual cycle phase of participants. At the fourth day of each menstrual cycle venous blood samples were collected for BDNF measurement by ELISA method. Before intervention, BDNF levels and mean scores of PMS symptoms (mood, behavioral and physical symptoms) between two groups showed no significant differences. But in curcumin group first, second and third cycles after interventions BDNF levels were significantly higher and mean scores of PMS symptoms were significantly less than placebo group. Based on our results part of these beneficial effects of curcumin may be mediated through enhancing serum BDNF levels in women with PMS.

Perinatal exposure to di-(2-ethylhexyl) phthalate affects anxiety- and depression-like behaviors in mice

Di-(2-ethylhexyl) phthalate (DEHP) is an environmental endocrine disrupter. The present study investigated the effect of DEHP on emotional behavior of mice following perinatal exposure (10, 50, and 200 mg kg(-1) d(-1)) from gestation day 7 through postnatal day 21. The results showed that, in pubertal males (6-w-old), DEHP decreased the time spent in the open arms and the number of entries into them in elevated plus maze and decreased the time in the mirrored chamber and in the light-box; in pubertal females, DEHP decreased the time spent in the open arms and the number of entries into them, suggesting that DEHP exposure made a anxiogenic effect in pubertal offspring regardless of sex. While DEHP effect on anxiety of adult (12-w-old) displayed sex differences, with decreased time spent in the open arms in the adult females. Perinatal exposure to DEPH significantly extended the time of immobility in forced swim task of pubertal offspring and adulthood regardless of sex. Furthermore, DEHP down-regulated the expressions of androgen receptor (AR) in pubertal male hippocampus and of estrogen receptor (ER) β in pubertal female and adult hippocampus of both sexes and inhibited the phosphorylation of ERK1/2 of hippocampus in pubertal mice and adult males. These results suggest that exposure to DEHP early in life affected the anxiety- and depressive-like behaviors of pubertal offspring and even adult. The disruption of gonadal hormones' modulation of behaviors due to down-regulation of AR or ERβ in the hippocampus may be associated with the aggravated anxiety- and depression-like status induced by DEHP.

Sex-specific effects of long-term exposure to bisphenol-A on anxiety- and depression-like behaviors in adult mice

Humans are routinely exposed to low levels of bisphenol A (BPA), an environmental endocrine disruptor, which is widely used in the production of polycarbonate plastics. The effects of perinatal exposure to BPA have been shown to affect various aspects of social behaviors such as anxiety and depression in adult offspring. Because sex hormones play a critical role in neurobehavior in adulthood, it is possible that long-term exposure to BPA has widespread effects on these emotional behaviors in adulthood. In the present study, adult mice were exposed to BPA at dosages of 0.04, 0.4, 4, 40 mg kg(-1)d(-1) for 12 weeks. A behavioral assay was performed using the open field test (OFT), mirrored maze, the elevated plus maze (EPM), and the forced swim task. The results showed that, after exposure to BPA at 0.4-40 mg kg(-1)d(-1), the number of open arm entries and the time spent in them in the elevated plus maze task were reduced in males but increased in females, and thus eliminating or reversing sex differences in these behaviors. BPA at 0.04-40 mg kg(-1)d(-1) increased the immobility of male mice in the forced swimming test. Furthermore, BPA (0.4-40 mg kg(-1)d(-1)) significantly decreased brain level of testosterone in males, but no significant influence was found in serum and the brain levels of estradiol in females. Western blot analysis further indicated that BPA at 0.4, 4, or 40 mg kg(-1)d(-1) significantly down-regulated the protein level of estrogen receptor β (ERβ) in the hippocampus of the adult males but not females, and inhibited the protein level of GABA(A)α2 receptor in hippocampus of males but promoted that of females. These results suggest that long-term exposure to BPA sex specifically affects anxiety- and depression-like behaviors in adult mice. Changes in the levels of GABA(A)α2 receptor and ERβ proteins of hippocampus might be associated with BPA-induced changes in these emotional behaviors.

Stress exposure prior to fear acquisition interacts with estradiol status to alter recall of fear extinction in humans

Classical fear acquisition and extinction are important models for the etiology and treatment of anxiety disorders such as posttraumatic stress disorder (PTSD). Women are at a higher risk for PTSD than men. Levels of circulating 17-β estradiol (E2) in women have been linked to deficits in fear extinction and extinction recall. In PTSD, fear learning coincides with acute traumatic stress. However, little is known about the possible interaction between stress exposure and hormone status on fear acquisition and extinction learning. In a 2-day, 2×3 between-subjects design with healthy participants, we examined the effects of stress (psychosocial stressor vs. control, placed 45 min prior to conditioning) and natural E2-status on differential fear conditioning, covering fear acquisition, immediate extinction (Day 1), and 24h-delayed extinction recall (Day 2). To operationalize E2-status, we compared women in the early follicular phase (EF) of their menstrual cycle (low E2, low progesterone plasma levels), women in the midcycle phase (MC, high E2, low progesterone), and men. Conditioning was indicated by differential skin conductance responses. We found an interaction between stress exposure and natural E2-status in women only: In MC-women, extinction recall on Day 2 (24h after initial extinction training) was better when fear acquisition had been preceded by stress. In EF-women, the inverse was true. We show that extinction recall of conditioned fear acquired after stress depends on estrogen status in women. Therefore, extinction-based exposure therapy in free-cycling female anxiety patients should take cycle status into account.

The influence of the HPG axis on stress response and depressive-like behaviour in a transgenic mouse model of Huntington's disease

Huntington's disease (HD) is an autosomal dominant, neurodegenerative disease caused by a CAG tandem repeat mutation encoding a polyglutamine tract expansion in the huntingtin protein. Depression is among the most common affective symptoms in HD but the pathophysiology is unclear. We have previously discovered sexually dimorphic depressive-like behaviours in the R6/1 transgenic mouse model of HD at a pre-motor symptomatic age. Interestingly, only female R6/1 mice display this phenotype. Sexual dimorphism has not been explored in the human HD population despite the well-established knowledge that the clinical depression rate in females is almost twice that of males. Female susceptibility suggests a role of sex hormones, which have been shown to modulate stress response. There is evidence suggesting that the gonads are adversely affected in HD patients, which could alter sex hormone levels. The present study examined the role sex hormones play on stress response in the R6/1 mouse model of HD, in particular, its modulatory effect on the hypothalamic-pituitary-adrenal (HPA) axis and depression-like behaviour. We found that the gonads of female R6/1 mice show atrophy at an early age. Expression levels of gonadotropin-releasing hormone (GnRH) were decreased in the hypothalamus of female HD mice, relative to wild-type female littermates, as were serum testosterone levels. Female serum estradiol levels were not significantly changed. Gonadectomy surgery reduced HPA-axis activity in female mice but had no effect on behavioural phenotypes. Furthermore, expression of the oestrogen receptor (ER) α gene was found to be higher in the adrenal cells of female HD mice. Finally, administration of an ERβ agonist diarylpropionitrile (DPN) rescued depressive-like behaviour in the female HD mice. Our findings provide new insight into the pathogenesis of sexually dimorphic neuroendocrine, physiological and behavioural endophenotypes in HD, and suggest a new avenue for therapeutic intervention.

Sex differences in the adolescent developmental trajectory of parvalbumin interneurons in the hippocampus: a role for estradiol

OBJECTIVE

Gender differences in the neurodevelopmental disorder, schizophrenia, have been described for nearly all features of the illness. Reduced hippocampal expression of the GABAergic interneuron marker, parvalbumin (PV), and GABA synthesizing enzyme, GAD67, are consistently reported in schizophrenia. However, little is known of the expression patterns of hippocampal PV and GAD67 during adolescence and their interaction with sex steroid hormones during adolescent development. This study examined the effects of altered sex steroid hormone levels during adolescence on protein levels of PV, GAD67 and estrogen receptors (ERα/β) in the hippocampus of mice.

METHODS

Protein expression of PV and GAD67 was measured in the dorsal (DHP) and ventral (VHP) hippocampus of female and male C57Bl/6 mice by Western blot in a week by week analysis from pre-pubescence to adulthood (week 3-12). Fluorescent immunohistochemistry (IHC) was used to investigate the relationship between ERs and PV(+) cells in the hippocampus of female mice at young adulthood (week 10-11). To further examine the role of sex steroid hormones on PV and GAD67 expression, gonadectomy and hormone replacement was done at 5 weeks of age.

RESULTS

Female mice showed a significant gradual increase in PV expression from 3 to 12 weeks of age in the DHP and VHP which correlated with serum 17β-estradiol levels. Fluorescent IHC showed approximately 30-50% co-localization of ER-α in PV(+) cells in the female DHP and VHP (dentate gryus/hilus and CA1-CA3). Adolescent ovariectomy significantly reduced PV expression in the DHP but not VHP of female mice, while 17β-estradiol replacement prevented this deficit in DHP PV levels. ER-α expression, but not ER-β, was also reduced in the DHP following ovariectomy with no significant effect of 17β-estradiol replacement. In contrast to female mice, male mice did not show any significant changes in hippocampal PV/GAD67 expression throughout adolescent development. Furthermore, adolescent castration and treatment with testosterone or dihydrotestosterone produced no changes in PV/GAD67 expression.

CONCLUSIONS

Our data suggest a differential developmental trajectory of PV expression between the sexes and manipulating circulating levels of sex steroid hormones by ovariectomy alters this trajectory in a region-dependent manner. This may be mediated via ER-α signaling as this receptor was found to be co-localized with PV(+) cells in the female mouse hippocampus. Alternative mechanisms of 17β-estradiol-induced regulation of PV expression are also discussed herein. Together, results from the present study may offer more insight into neurodevelopmental disorders, including schizophrenia, where sex steroid hormones and GABAergic markers are implicated in the pathophysiology of the illness.

Antenatal prediction of postpartum depression with blood DNA methylation biomarkers

Postpartum depression (PPD) affects ∼10-18% of women in the general population and results in serious consequences to both the mother and offspring. We hypothesized that predisposition to PPD risk is due to an altered sensitivity to estrogen-mediated epigenetic changes that act in a cell autonomous manner detectable in the blood. We investigated estrogen-mediated epigenetic reprogramming events in the hippocampus and risk to PPD using a cross-species translational design. DNA methylation profiles were generated using methylation microarrays in a prospective sample of the blood from the antenatal period of pregnant mood disorder patients who would and would not develop depression postpartum. These profiles were cross-referenced with syntenic locations exhibiting hippocampal DNA methylation changes in the mouse responsive to long-term treatment with 17β-estradiol (E2). DNA methylation associated with PPD risk correlated significantly with E2-induced DNA methylation change, suggesting an enhanced sensitivity to estrogen-based DNA methylation reprogramming exists in those at risk for PPD. Using the combined mouse and human data, we identified two biomarker loci at the HP1BP3 and TTC9B genes that predicted PPD with an area under the receiver operator characteristic (ROC) curve (area under the curve (AUC)) of 0.87 in antenatally euthymic women and 0.12 in a replication sample of antenatally depressed women. Incorporation of blood count data into the model accounted for the discrepancy and produced an AUC of 0.96 across both prepartum depressed and euthymic women. Pathway analyses demonstrated that DNA methylation patterns related to hippocampal synaptic plasticity may be of etiological importance to PPD.

Stress and eating disorder behavior in anorexia nervosa as a function of menstrual cycle status

OBJECTIVE

Fluctuations in ovarian hormones during the menstrual cycle and psychosocial stress contribute to eating disorder (ED) behavior.

METHOD

Using ecological momentary assessment techniques, this study examined relationships between stress and binge eating, self-induced vomiting, and dietary restriction based on menstrual cycle status in anorexia nervosa (AN). One hundred nine females with full and subthreshold AN (17-45 years old) recorded ED behavior and stress ratings over 2 weeks. Using hierarchical linear modeling, individuals with eumenorrhea and those with amenorrhea or oligomenorrhea were compared.

RESULTS

Following episodes of meal skipping, momentary stress decreased in individuals with normal menstrual cycles and increased in those with irregular menstrual cycles.

DISCUSSION

Results suggest that changes in stress severity in response to food restriction may differ based on ovarian hormonal status and may be a mechanism by which AN is maintained in individuals without menstrual disturbance.

Special biological issues in the management of women with schizophrenia

Schizophrenia is a debilitating and pervasive mental illness with devastating effects on psychological, cognitive and social wellbeing, and for which current treatment options are far from ideal. Gender differences and the influence of the female reproductive life cycle on the onset, course and symptoms of schizophrenia and the discovery of estrogen's remarkable psychoprotective properties in animal models led to the proposal of the 'estrogen protection hypothesis' of schizophrenia. This has fueled the recent successful investigation of estradiol as a potential adjuvant therapeutic agent in the management of schizophrenia in women. This review explains the scientific rationale behind the estrogen hypothesis and how it can be clinically utilized to address concerns unique to the care of women with schizophrenia.

Progression from amnesic mild cognitive impairment to Alzheimer's disease: ESR1 and ESR2 polymorphisms and APOE gene

BACKGROUND

Many genes have been studied to determine how they might be involved in Alzheimer's disease (AD). Estrogens have a protective effect in the central nervous system. The mechanisms of action of estrogens are mediated by two estrogen receptors (ERs), ERα and ERβ. Thus, these genes could also play a role in the progression of amnesic mild cognitive impairment (MCIa) to AD. The aim of this study was to examine the role of ER single nucleotide polymorphisms (SNPs) as a risk factor for MCIa, as well as the interaction with apolipoprotein E (APOE) ε4 in the progression to AD.

METHODS

79 MCIa patients and 138 healthy controls were analyzed. SNPs were genotyped via restriction fragment length polymorphisms and real-time PCR, RT-PCR or RT-PCR (TaqMan) assays.

RESULTS

There is a lack of association between MCIa patients who converted to AD and ER SNPs. APOE ε4 allele is an independent risk factor of MCIa (OR=1.86; 95% CI=1.02-3.38, p=0.042) with a high prevalence in converted subjects. APOE ε4 is able to predict the progression from MCIa patients to AD (OR=2.55; 95% CI=1.20-5.42, p=0.015).

CONCLUSIONS

The presence of the APOE ε4 allele, and not the alleles of ER SNPs, is a risk factor for MCIa. Furthermore, APOE genotype seems to predict the conversion from MCIa to AD.

Role of estrogen treatment in the management of schizophrenia

Increasing evidence from epidemiological, preclinical and clinical studies suggests that estrogens may exert psychoprotective effects in schizophrenia. Observations of gender differences in the onset and course of schizophrenia have prompted exploration of the effects of estrogen on the CNS. The aim of this paper is to provide an overview of different applications of adjunctive estrogen as a possible treatment for symptoms of schizophrenia in both men and women. Recent trials have suggested that estrogen augmentation therapy may be able to enhance the management of schizophrenia; however, the clinical application of estrogen as a treatment has been limited by potential side effects, the most worrying being breast and uterine cancer in women, and feminization in men. Selective estrogen receptor modulators (SERMs), however, may offer therapeutic benefits for both men and women with schizophrenia without posing threat to breast and uterine tissue and without feminizing effects. The use of estrogen opens up new possibilities for both men and women in the treatment of severe mental illnesses such as schizophrenia. With further preclinical and clinical research, it is hoped that this promising field of hormone modulation can continue to evolve and eventually be translated into real therapeutic potential.

Perinatal BPA exposure demasculinizes males in measures of affect but has no effect on water maze learning in adulthood

Bisphenol A (BPA) is an endocrine disrupting agent that can alter the normal gonadal steroid-sensitive sexual differentiation of the brain and behavior. While reproductive behavior and physiology are known to be altered by perinatal exposure to this compound, less is known about BPA's effects on sex differences in learning and measures of affect. In order to evaluate the effects of perinatal BPA treatment on learning and affect in adulthood, we exposed rats to one of five doses of BPA through gestation and lactation then examined adult behavior in the Morris Water Maze (MWM), the Elevated Plus Maze (EPM) and the Forced Swim Test (FST). No effect of BPA was observed in the MWM, but on both the EPM and FST, low doses (5 μg/kg) of BPA eliminated sex differences found between controls; furthermore, a non-monotonic dose-response observed in previous studies was confirmed for these tasks. Overall, our study adds to the growing data suggesting that BPA interferes with the normal development of affective behaviors in a non-linear, dose-dependent manner.

Hormones and schizophrenia

PURPOSE OF REVIEW

It is a well established fact that many serious mental illnesses, in particular psychoses such as schizophrenia, may have a significant hormonal aetiological component. This study aims to discuss the oestrogen protection hypothesis of schizophrenia in particular, with an emphasis on findings from the recent literature in support of this theory.

RECENT FINDINGS

Epidemiological and life-cycle data point to significant differences in the incidence and course of schizophrenia between men and women, suggesting a protective role of oestrogen. In-vitro and in-vivo preclinical research has confirmed oestradiol's interactions with central neurotransmitter systems implicated in the pathogenesis of schizophrenia, whereas results from randomized controlled trials investigating the antipsychotic potential of oestrogen have been promising. Research into other neuroactive hormones with possible effects on mental state is a field still in its infancy but is evolving rapidly.

SUMMARY

Schizophrenia and related psychoses are pervasive and debilitating conditions, for which currently available treatments are often only partially effective and entail a high risk of serious side effects. Thus, new therapeutic strategies are needed, and the literature reviewed here suggests that hormones such as oestrogen could be a viable option. It is hoped that, with further research and larger trials, the oestrogen hypothesis can be translated into effective clinical practice.

The role of oestrogen and other hormones in the pathophysiology and treatment of schizophrenia

The theory that many serious mental illnesses, in particular psychoses such as schizophrenia, may have a significant hormonal aetiological component is fast gaining popularity and the support of scientific evidence. Oestrogen in particular has been substantially investigated as a potential mediator of brain function in schizophrenia. Epidemiological and life-cycle data point to significant differences in the incidence and course of schizophrenia between men and women suggests a protective role of oestrogen. In vitro and in vivo preclinical research confirms oestradiol's interactions with central neurotransmitter systems implicated in the pathogenesis of schizophrenia, while results from randomised controlled trials investigating the antipsychotic potential of oestrogen have been positive. Research into other neuroactive hormones with possible effects on mental state is a rapidly evolving field that may hold new promise. Given that schizophrenia and related psychoses are pervasive and debilitating conditions for which currently available treatments are often only partially effective and entail a high risk of serious side-effects, novel therapeutic strategies are needed. The literature reviewed in this paper suggests that hormones such as oestrogen could be a viable option, and it is hoped that with further research and larger trials, the oestrogen hypothesis can be translated into effective clinical practice.

Association of estrogen receptor β gene polymorphisms with vascular dementia in women

The objective of the present study was to explore a potential association between the estrogen receptor β (ERβ) gene polymorphisms and vascular dementia (VaD) in women. The relationship of two polymorphisms (rs944050 and rs4986938) and their associated haplotypes in the ERβ gene with VaD were examined in 121 Chinese Han women (>50 years of age) including 61 with VaD and 60 healthy age-matched controls. The potential associations were evaluated using unconditional logistic regression. The variant allele G of rs944050 in the ERβ gene increased the risk of VaD (odds ratio = 2.02, 95% confidence interval = 1.08-3.77). In haplotype analyses, the ERβ haplotype containing the polymorphism rs944050 variant allele and the polymorphism rs4986938 wild-type allele was associated with VaD (odds ratio = 1.70, 95% confidence interval = 1.03-2.84). The polymorphism rs944050 in the ERβ gene was associated with an increased risk of VaD in Chinese Han women. Further studies regarding the association between the ERβ gene polymorphisms and VaD are needed to confirm these findings.

Estrous cycle stage influences on neuronal responsiveness to repeated anxiogenic stress in female rats

Experiments were carried out to investigate (i) whether estrous cycle stage influences nociceptive responsiveness to anxiogenic stress and (ii) whether prior experience of the stressor modifies the response. Exposure to mild anxiogenic vibration stress evoked hyperalgesia, reflected by a decrease in tail flick latency, only in animals in the late diestrus phase. Stress evoked hyperalgesia in late diestrus regardless of whether the rat was experiencing the stress for the first time or had been exposed to the stress previously, when in another cycle stage. Whilst the behavioral response to stress appeared to be determined exclusively by estrous cycle stage, the stress-evoked pattern of Fos expression in the periaqueductal grey matter (PAG) depended not only on cycle stage but also on whether the rat had previous experience of the stress. First exposure to stress in late diestrus evoked a 50% decrease in Fos expression compared to non-stressed controls, particularly in the lateral and dorsolateral sectors of the rostral PAG. In contrast, in experienced rats in late diestrus the pattern of Fos expression increased up to 4-fold, particularly in the ventral half of the caudal PAG but also in the lateral and dorsolateral parts. At other cycle stages Fos expression was not changed except for an increase in rats in proestrus. The results suggest that in females, changes in gonadal hormone levels during the estrous cycle impact significantly on the processing of fear-inducing stimuli by the PAG. These hormonal influences may also influence how the PAG responds to a subsequent anxiogenic challenge.

Interactive effects of age and estrogen on cortical neurons: implications for cognitive aging

In the past few decades it has become clear that estrogen signaling plays a much larger role in modulating the cognitive centers of the brain than previously thought possible. We have developed a nonhuman primate (NHP) model to investigate the relationships between estradiol (E) and cognitive aging. Our studies of cyclical E treatment in ovariectomized (OVX) young and aged rhesus monkeys have revealed compelling cognitive and synaptic effects of E in the context of aging. Delayed response (DR), a task that is particularly dependent on integrity of dorsolateral prefrontal cortex (dlPFC) area 46 revealed the following: (1) that young OVX rhesus monkeys perform equally well whether treated with E or vehicle (V), and (2) that aged OVX animals given E perform as well as young adults with or without E, whereas OVX V-treated aged animals display significant DR impairment. We have analyzed the structure of layer III pyramidal cells in area 46 in these same monkeys. We found both age and treatment effects on these neurons that are consistent with behavioral data. Briefly, reconstructions of pyramidal neurons in area 46 from these monkeys showed that cyclical E increased the density of small, thin spines in both young and aged monkeys. However, this effect of E was against a background of age-related loss of small, thin spines, leaving aged V-treated monkeys with a particularly low density of these highly plastic spines, and vulnerable to cognitive decline. Our current interpretation is that E not only plays a critically important role in maintaining spine number, but also enables synaptic plasticity through a cyclical increase in small highly plastic spines that may be stabilized in the context of learning. Interestingly, recent studies demonstrate that chronic E is less effective at inducing spinogenesis than cyclical E. We have begun to link certain molecular attributes of excitatory synapses in area 46 to E effects and cognitive performance in these monkeys. Given the importance of synaptic estrogen receptor α (ER-α) in rat hippocampus, we focused our initial studies on synaptic ER-α in area 46. Three key findings have emerged from these studies: (1) synaptic ER-α is present in axospinous synapses in area 46; (2) it is stable across treatment and age groups (which is not the case in rat hippocampus); and (3) the abundance and distribution of synaptic ER-α is a key correlate of individual variation in cognitive performance in certain age and treatment groups. These findings have important implications for the design of hormone treatment strategies for both surgically and naturally menopausal women. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain.