Alteration in estrogen receptor alpha mRNA levels in frontal cortex and hippocampus of patients with major mental illness

Perspective: the evolution of hormones and person perception-a quantitative genetic framework

Evolutionary biology provides a unifying theory for testing hypotheses about the relationship between hormones and person perception. Person perception usually receives attention from the perspective of sexual selection. However, because person perception is one trait in a suite regulated by hormones, univariate approaches are insufficient. In this Perspectives article, quantitative genetics is presented as an important but underutilized framework for testing evolutionary hypotheses within this literature. We note tacit assumptions within the current literature on psychiatric genetics, which imperil the interpretation of findings thus far. As regulators of a diverse manifold of traits, hormones mediate tradeoffs among an array of functions. Hormonal pleiotropy also provides the basis of correlational selection, a process whereby selection on one trait in a hormone-mediated suite generates selection on the others. This architecture provides the basis for conflicts between sexual and natural selection within hormone-mediated suites. Due to its role in person perception, psychiatric disorders, and reproductive physiology, the sex hormone estrogen is highlighted as an exemplar here. The implications of this framework for the evolution of person perception are discussed. Empirical quantification of selection on traits within hormone-mediated suites remains an important gap in this literature with great potential to illuminate the fundamental nature of psychiatric disorders.

Role of estrogen in sex differences in memory, emotion and neuropsychiatric disorders

Estrogen regulates a wide range of neuronal functions in the brain, such as dendritic spine formation, remodeling of synaptic plasticity, cognition, neurotransmission, and neurodevelopment. Estrogen interacts with intracellular estrogen receptors (ERs) and membrane-bound ERs to produce its effect via genomic and non-genomic pathways. Any alterations in these pathways affect the number, size, and shape of dendritic spines in neurons associated with psychiatric diseases. Increasing evidence suggests that estrogen fluctuation causes changes in dendritic spine density, morphology, and synapse numbers of excitatory and inhibitory neurons differently in males and females. In this review, we discuss the role of estrogen hormone in rodents and humans based on sex differences. First, we explain estrogen role in learning and memory and show that a high estrogen level alleviates the deficits in learning and memory. Secondly, we point out that estrogen produces a striking difference in emotional memories in men and women, which leads them to display sex-specific differences in underlying neuronal signaling. Lastly, we discuss that fluctuations in estrogen levels in men and women are related to neuropsychiatric disorders, including schizophrenia, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), bipolar disorder (BPD), major depressive disorder (MDD), substance use disorder (SUD), and anxiety disorders.

Peering into the Brain's Estrogen Receptors: PET Tracers for Visualization of Nuclear and Extranuclear Estrogen Receptors in Brain Disorders

Estrogen receptors (ERs) play a multitude of roles in brain function and are implicated in various brain disorders. The use of positron emission tomography (PET) tracers for the visualization of ERs' intricate landscape has shown promise in oncology but remains limited in the context of brain disorders. Despite recent progress in the identification and development of more selective ligands for various ERs subtypes, further optimization is necessary to enable the reliable and efficient imaging of these receptors. In this perspective, we briefly touch upon the significance of estrogen signaling in the brain and raise the setbacks associated with the development of PET tracers for identification of specific ERs subtypes in the brain. We then propose avenues for developing efficient PET tracers to non-invasively study the dynamics of ERs in the brain, as well as neuropsychiatric diseases associated with their malfunction in a longitudinal manner. This perspective puts several potential candidates on the table and highlights the unmet needs and areas requiring further research to unlock the full potential of PET tracers for ERs imaging, ultimately aiding in deepening our understanding of ERs and forging new avenues for potential therapeutic strategies.

Expression and function of estrogen receptors and estrogen-related receptors in the brain and their association with Alzheimer's disease

While estrogens are well known for their pivotal role in the female reproductive system, they also play a crucial function in regulating physiological processes associated with learning and memory in the brain. Moreover, they have neuroprotective effects in the pathogenesis of Alzheimer's disease (AD). Importantly, AD has a higher incidence in older and postmenopausal women than in men, and estrogen treatment might reduce the risk of AD in these women. In general, estrogens bind to and activate estrogen receptors (ERs)-mediated transcriptional machineries, and also stimulate signal transduction through membrane ERs (mERs). Estrogen-related receptors (ERRs), which share homologous sequences with ERs but lack estrogen-binding capabilities, are widely and highly expressed in the human brain and have also been implicated in AD pathogenesis. In this review, we primarily provide a summary of ER and ERR expression patterns in the human brain. In addition, we summarize recent studies on their role in learning and memory. We then review and discuss research that has elucidated the functions and importance of ERs and ERRs in AD pathogenesis, including their role in Aβ clearance and the reduction of phosphorylated tau levels. Elucidation of the mechanisms underlying ER- and ERR-mediated transcriptional machineries and their functions in healthy and diseased brains would provide new perspectives for the diagnosis and treatment of AD. Furthermore, exploring the potential role of estrogens and their receptors, ERs, in AD will facilitate a better understanding of the sex differences observed in AD, and lead to novel sex-specific therapeutic approaches.

The Effect of Cumulative Lifetime Estrogen Exposure on Cognition in Depressed Versus Non-Depressed Older Women

OBJECTIVES

Two-thirds of individuals living with Alzheimer's disease are women. Declining estrogen levels influence mood and cognition. Cumulative lifetime estrogen exposure (CLEE) correlates with cognition later in life. We examined the relationship of CLEE to depression and cognition in older women with major depression compared to non-depressed women.

DESIGN

Older women (age ≥60 years) with depression were compared to non-depressed women using a lifetime estrogen exposure questionnaire. CLEE was defined as combined durations of reproductive span (age of menopause minus age of menarche) and any post-menopausal hormone replacement therapy use. Higher vs lower CLEE groups were based on a median of 474 months of estrogen exposure.

SETTING

University hospital outpatient research program.

PARTICIPANTS

135 women ≥60 years; 64 depressed and 71 non-depressed.

MEASURMENTS

Participants completed a comprehensive cognitive test battery. General linear models were used to examine the association between cognitive domain scores and CLEE in depressed and non-depressed women, controlling for age, education, and ethnicity.

RESULTS

Depressed and non-depressed groups had significantly different levels of CLEE, measured in months: mean 495.7 (SD 108.6) vs 456.4 (SD 66.0) months, F(1,130) = 5.01, p = .03. Within the non-depressed participants, higher CLEE was associated with improved delayed recall (F(1,59) = 5.94, p = .02, effect size = .61), while no such relationship was observed in the depressed group.

CONCLUSION

Higher CLEE was associated with improvement in delayed recall among non-depressed, but not among depressed participants. This suggests a protective role of estrogen on memory in non-depressed older postmenopausal women. Further research should examine the role of the CLEE in antidepressant response and cognitive decline.

Perinatal low-dose bisphenol AF exposure impairs synaptic plasticity and cognitive function of adult offspring in a sex-dependent manner

Bisphenol AF (BPAF), a kind of the ideal substitutes of Bisphenol A (BPA), has frequently been detected in environmental media and biological samples. Numerous studies have focused on the reproductive toxicity, cardiotoxicity and endocrine disrupting toxicity of BPAF. However, little evidence is available on neurodevelopmental toxicity of BPAF. Here, our study is to evaluate the effect of perinatal BPAF exposure (0, 0.34, 3.4 and 34 mg/kg body weight/day, correspond to Ctrl, low-, medium- and high-dose groups) on the cognitive function of adult mouse offspring. This study firstly found that perinatal BPAF exposure caused cognitive impairments of mouse offspring, in which male offspring was more sensitive than female offspring in low- and medium-dose BPAF groups. Furthermore, the dendritic arborization and complexity of hippocampal CA1 and DG neurons in male offspring were impaired in all BPAF groups, and these effects were only found in high-dose BPAF group for female offspring. The damage of BPAF to dendritic spines, and the structural basis of learning and memory, was found in male offspring but not in females. Correspondingly, perinatal BPAF exposure significantly downregulated the expressions of hippocampal PSD-95 and Synapsin-1 proteins, and male offspring was more vulnerable than female offspring. Meanwhile, we explored the alteration of hippocampal estrogen receptors (ERs) to explain the sex specific impairment of cognitive function in low- and medium-dose BPAF groups. The results showed that perinatal BPAF exposure significantly decreased the expression of ERα in male offspring in a dose-dependent manner, but not in female offspring. In addition, we found that perinatal BPAF exposure can disordered the balance of oxidation and antioxidation in hippocampus of male offspring. In summary, perinatal low-dose bisphenol AF exposure impairs synaptic plasticity and cognitive function of adult offspring in a sex-dependent manner. The present results provide a pierce of potential mechanism of BPAF-caused neurodevelopmental toxicity.

Estrogen Receptor α Agonist is Beneficial for Young Female Rats Against Chronic Unpredicted Mild Stress-Induced Depressive Behavior and Cognitive Deficits

BACKGROUND

Women are reported more likely to develop depression and dementia. However, the involved mechanism is poorly understood.

OBJECTIVE

Here, we clarified the role of estrogen receptor α (ERα) in depression and cognitive deficit in young female rats.

METHODS

After being exposed to 7-weeks' chronic unpredicted mild stress (CUMS), the depression resilient rats (Res rats) and depressed rats (Dep rats) were selected according to their records in sucrose preference test, forced swimming test, and open field test. Their cognition abilities were tested by Morris water maze. Proteomic assay, immunoprecipitation, western blotting, immunohistochemical, and Nissl staining were also used to understand the involved mechanism.

RESULTS

Compared with control rats and Res rats, Dep rats showed cognitive deficits and hippocampal impairments revealed by proteomic data, neuron losses, increased cleaved caspase-3, β-catenin phosphorylation, and glycogen synthase kinase3β (GSK3β) activation. As ERα, but not ERβ, was found declined in hippocampi of Dep rats, 4,4k,4a-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT, an ERα agonist, 1 mg/kg/day), was used to treat Dep rats (Dep + PPT). Twenty days later, the depressive behaviors, cognition deficits, and hippocampal neuron loss were rescued in Dep + PPT rats. Furthermore, Res and Dep + PPT rats had higher levels of β-catenin combined with ERα and lower levels of β-catenin combined with GSK3β than Dep rats in hippocampi.

CONCLUSION

These results demonstrated hippocampal ERα is an important pro-resilient factor in CUMS-induced depressive behaviors and cognitive deficits. It was also given that the neuroprotection afforded by hippocampal ERα/Wnt interactions have significant implications for cognition and emotion in young females.

Estrogen pendulum in schizophrenia and Alzheimer's disease: Review of therapeutic benefits and outstanding questions

Although produced largely in the periphery, gonadal steroids play a key role in regulating the development and functions of the central nervous system and have been implicated in several chronic neuropsychiatric disorders, with schizophrenia and Alzheimer's disease (AD) most prominent. Despite major differences in pathobiology and clinical manifestations, in both conditions, estrogen transpires primarily with protective effects, buffering the onset and progression of diseases at various levels. As a result, estrogen replacement therapy (ERT) emerges as one of the most widely discussed adjuvant interventions. In this review, we revisit evidence supporting the protective role of estrogen in schizophrenia and AD and consider putative cellular and molecular mechanisms. We explore the underlying functional processes relevant to the manifestation of these devastating conditions, with a focus on synaptic transmission and plasticity mechanisms. We discuss specific effects of estrogen deficit on neurotransmitter systems such as cholinergic, dopaminergic, serotoninergic, and glutamatergic. While the evidence from both, preclinical and clinical reports, in general, are supportive of the protective effects of estrogen from cognitive decline to synaptic pathology, numerous questions remain, calling for further research.

Serum estradiol as a blood-based biomarker predicting hormonal treatment outcomes in women with schizophrenia

Patients diagnosed with schizophrenia display substantial heterogeneity in terms of their clinical presentations, and treatment response. Accumulating research suggests that such high diversity may reflect distinct biological subtypes with differentially affected underlying neurobiology. Novel treatments, including sex hormone estradiol treatments, provide alternative efficacious treatment avenues but also should be studied within the context of potential heterogeneity. This repeated-measures study characterised the association between hormone levels (estrogen, progesterone, testosterone, prolactin, FSH, LH, DHEA) and symptom treatment outcomes (defined by The Positive and Negative Syndrome Scale (PANSS)) across a 56-day study of 200 ug adjunctive estradiol treatment in women with schizophrenia. Group-based trajectory models was used to account for potential heterogeneity (subgroups). Receiver operating characteristic (ROC) curves were evaluated to define the predictive value of endogenous estradiol levels as a treatment-response biomarker of estradiol treatment. The results generated two subgroups; a treatment-responder group who demonstrated decreasing PANSS scores across time, and a treatment non-responder group, demonstrating stable PANSS scores across time. The treatment-responder subgroup was significantly negatively predicted by estradiol blood level (b= -2.34, SE= 1.17, p = 0.047), while FSH blood level was positively associated with the treatment non-responders (b= 7.14, SE= 2.54, p = 0.008). ROC for day 28, 56 time points yielded area under the curve of 0.52 and 0.55, respectively. Harrell's C-statistic = 0.59. This is the first study to identify endocrine markers in blood serum predicting response to estradiol treatment in female schizophrenia patients, highlighting the existence of heterogeneity of response, indicative of molecular subtypes. Characterising the differential underlying biology of the subgroups may lead to better targeted, specific treatments in the future.(ClinicalTrials.gov Identifier: NCT00357006). https://www.clinicaltrials.gov/ct2/show/NCT00357006.

Quercetin exerts antidepressant and cardioprotective effects in estrogen receptor α-deficient female mice via BDNF-AKT/ERK1/2 signaling

Brain-derived neurotrophic factor (BDNF) is the potential link between depression and cardiovascular disease and estrogen receptor α (ERα), an estrogen-mediated major regulator, plays an important role in protecting against depression and cardiovascular disease. However, the relationship between BDNF and ERα remains obscure. Herein, quercetin (QUE), a kind of plant flavonoids and existed in many vegetables and fruits, was found to simultaneously reverse ERα-/--induced depression-like and cardiac dysfunction by reducing immobility time in the tail suspension test (TST) and forced swimming test (FST), and decreasing systolic blood pressure and activating the apoptosis-related proteins, BDNF, tropomyosin-related kinase B (TrkB), protein kinase B (AKT), and extracellular regulatory protein kinase (ERK1/2) in the hippocampal and cardiac tissues of female mice. These findings suggested that ERα might be involved in the regulation of BDNF activity, thereby regulating depression-like and cardiovascular responses in female mice, and QUE exerted significant antidepressant and cardioprotective effects, at least in part, through BDNF-TrkB-AKT/ERK1/2 to effectively inhibit ERα-/--induced hippocampal and cardiac dysfunction.

Akkouh I, Hughes T, Frei E, A. Andreassen O, Djurovic S. Using iPSC Models to Understand the Role of Estrogen in Neuron-Glia Interactions in Schizophrenia and Bipolar Disorder

Schizophrenia (SCZ) and bipolar disorder (BIP) are severe mental disorders with a considerable disease burden worldwide due to early age of onset, chronicity, and lack of efficient treatments or prevention strategies. Whilst our current knowledge is that SCZ and BIP are highly heritable and share common pathophysiological mechanisms associated with cellular signaling, neurotransmission, energy metabolism, and neuroinflammation, the development of novel therapies has been hampered by the unavailability of appropriate models to identify novel targetable pathomechanisms. Recent data suggest that neuron-glia interactions are disturbed in SCZ and BIP, and are modulated by estrogen (E2). However, most of the knowledge we have so far on the neuromodulatory effects of E2 came from studies on animal models and human cell lines, and may not accurately reflect many processes occurring exclusively in the human brain. Thus, here we highlight the advantages of using induced pluripotent stem cell (iPSC) models to revisit studies of mechanisms underlying beneficial effects of E2 in human brain cells. A better understanding of these mechanisms opens the opportunity to identify putative targets of novel therapeutic agents for SCZ and BIP. In this review, we first summarize the literature on the molecular mechanisms involved in SCZ and BIP pathology and the beneficial effects of E2 on neuron-glia interactions. Then, we briefly present the most recent developments in the iPSC field, emphasizing the potential of using patient-derived iPSCs as more relevant models to study the effects of E2 on neuron-glia interactions.

The Role of Estrogen Receptors and Their Signaling across Psychiatric Disorders

Increasing evidence suggests estrogen and estrogen signaling pathway disturbances across psychiatric disorders. Estrogens are not only crucial in sexual maturation and reproduction but are also highly involved in a wide range of brain functions, such as cognition, memory, neurodevelopment, and neuroplasticity. To add more, the recent findings of its neuroprotective and anti-inflammatory effects have grown interested in investigating its potential therapeutic use to psychiatric disorders. In this review, we analyze the emerging literature on estrogen receptors and psychiatric disorders in cellular, preclinical, and clinical studies. Specifically, we discuss the contribution of estrogen receptor and estrogen signaling to cognition and neuroprotection via mediating multiple neural systems, such as dopaminergic, serotonergic, and glutamatergic systems. Then, we assess their disruptions and their potential implications for pathophysiologies in psychiatric disorders. Further, in this review, current treatment strategies involving estrogen and estrogen signaling are evaluated to suggest a future direction in identifying novel treatment strategies in psychiatric disorders.

Raloxifene augmentation in men and women with a schizophrenia spectrum disorder: A study protocol

Although acute psychotic symptoms are often reduced by antipsychotic treatment, many patients with schizophrenia are impaired in daily functioning due to the persistence of negative and cognitive symptoms. Raloxifene, a Selective Estrogen Receptor Modulator (SERM) has been shown to be an effective adjunctive treatment in schizophrenia. Yet, there is a paucity in evidence for raloxifene efficacy in men and premenopausal women. We report the design of a study that aims to replicate earlier findings concerning the efficacy of raloxifene augmentation in reducing persisting symptoms and cognitive impairment in postmenopausal women, and to extend these findings to a male and peri/premenopausal population of patients with schizophrenia. The study is a multisite, placebo-controlled, double-blind, randomised clinical trial in approximately 110 adult men and women with schizophrenia. Participants are randomised 1:1 to adjunctive raloxifene 120 mg or placebo daily during 12 weeks. The treatment phase includes measurements at three time points (week 0, 6 and 12), followed by a follow-up period of two years. The primary outcome measure is change in symptom severity, as measured with the Positive and Negative Syndrome Scale (PANSS), and cognition, as measured with the Brief Assessment of Cognition in Schizophrenia (BACS). Secondary outcome measures include social functioning and quality of life. Genetic, hormonal and inflammatory biomarkers are measured to assess potential associations with treatment effects. If it becomes apparent that raloxifene reduces psychotic symptoms and/or improves cognition, social functioning and/or quality of life as compared to placebo, implementation of raloxifene in clinical psychiatric practice can be considered.

Molecular alterations in the medial temporal lobe in schizophrenia

The medial temporal lobe (MTL) and its individual structures have been extensively implicated in schizophrenia pathophysiology, with considerable efforts aimed at identifying structural and functional differences in this brain region. The major structures of the MTL for which prominent differences have been revealed include the hippocampus, the amygdala and the superior temporal gyrus (STG). The different functions of each of these regions have been comprehensively characterized, and likely contribute differently to schizophrenia. While neuroimaging studies provide an essential framework for understanding the role of these MTL structures in various aspects of the disease, ongoing efforts have sought to employ molecular measurements in order to elucidate the biology underlying these macroscopic differences. This review provides a summary of the molecular findings in three major MTL structures, and discusses convergent findings in cellular architecture and inter-and intra-cellular networks. The findings of this effort have uncovered cell-type, network and gene-level specificity largely unique to each brain region, indicating distinct molecular origins of disease etiology. Future studies should test the functional implications of these molecular changes at the circuit level, and leverage new advances in sequencing technology to further refine our understanding of the differential contribution of MTL structures to schizophrenia.

Sex differences: Transcriptional signatures of stress exposure in male and female brains

More than two-thirds of patients suffering from stress-related disorders are women but over two-thirds of suicide completers are men. These are just some examples of the many sex differences in the prevalence and manifestations of stress-related disorders, such as major depressive disorder, post-traumatic stress disorder, and anxiety disorders, which have been extensively documented in clinical research. Nonetheless, the molecular origins of this sex dimorphism are still quite obscure. In response to this lack of knowledge, the NIH recently advocated implementing sex as biological variable in the design of preclinical studies across disciplines. As a result, a newly emerging field within psychiatry is trying to elucidate the molecular causes underlying the clinically described sex dimorphism. Several studies in rodents and humans have already identified many stress-related genes that are regulated by acute and chronic stress in a sex-specific fashion. Furthermore, current transcriptomic studies have shown that pathways and networks in male and female individuals are not equally affected by stress exposure. In this review, we give an overview of transcriptional studies designed to understand how sex influences stress-specific transcriptomic changes in rodent models, as well as human psychiatric patients, highlighting the use of different methodological techniques. Understanding which mechanisms are more affected in males, and which in females, may lead to the identification of sex-specific mechanisms, their selective contribution to stress susceptibility, and their role in the development of stress-related psychiatric disorders.

Prolactin, Estradiol and Testosterone Differentially Impact Human Hippocampal Neurogenesis in an In Vitro Model

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Human hippocampal progenitor cells (HPCs) and tissue express classical sex hormone receptors.

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Prolactin does not impact human HPCs maintained in a proliferative state.

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Prolactin increases neuronal differentiation of human HPCs only in the short term.

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Estradiol and testosterone both increase the cell density of proliferating HPCs.

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Estradiol and testosterone have no observed effect on differentiating HPCs.

Previous studies have indicated that sex hormones such as prolactin, estradiol and testosterone may play a role in the modulation of adult hippocampal neurogenesis (AHN) in rodents and non-human primates, but so far there has been no investigation of their impact on human hippocampal neurogenesis. Here, we quantify the expression levels of the relevant receptors in human post-mortem hippocampal tissue and a human hippocampal progenitor cell (HPC) line. Secondly, we investigate how these hormones modulate hippocampal neurogenesis using a human in vitro cellular model. Human female HPCs were cultured with biologically relevant concentrations of either prolactin, estradiol or testosterone. Bromodeoxyuridine (BrdU) incorporation, immunocytochemistry (ICC) and high-throughput analyses were used to quantify markers determining cell fate after HPCs were either maintained in a proliferative state or allowed to differentiate in the presence of these hormones. In proliferating cells, estrogen and testosterone increased cell density but had no clear effect on markers of proliferation or cell death to account for this. In differentiating cells, a 3-day treatment of prolactin elicited a transient effect, whereby it increased the proportion of microtubule-associated protein 2 (MAP2)-positive and Doublecortin (DCX)-positive cells, but this effect was not apparent after 7-days. At this timepoint we instead observe a decrease in proliferation. Overall, our study demonstrates relatively minor, and possibly short-term effects of sex hormones on hippocampal neurogenesis in human cells. Further work will be needed to understand if our results differ to previous animal research due to species-specific differences, or whether it relates to limitations of our in vitro model.

Evidence for enhanced androgen action in the prefrontal cortex of people with bipolar disorder but not schizophrenia or major depressive disorder

Anxiety and depressive disorders are more prevalent in hypogonadal men. Low testosterone levels are associated with greater negative symptoms and impaired cognition in men with schizophrenia. Thus, androgens may contribute to brain pathophysiology in psychiatric disorders. We investigated androgen-related mRNAs in post-mortem dorsolateral prefrontal cortex of psychiatric disorders. We also assessed androgen receptor (AR) CAG trinucleotide repeat length, a functional AR gene variant associated with AR gene expression, receptor activity, and circulating testosterone. AR CAG repeat length was determined from genomic DNA and AR and 5α-reductase mRNAs measured using quantitative PCR in schizophrenia, bipolar disorder and control cases [n = 35/group; Stanley Medical Research Institute (SMRI) Array collection]. Layer-specific AR gene expression was determined using in situ hybridisation in schizophrenia, bipolar disorder, major depressive disorder and control cases (n = 15/group; SMRI Neuropathology Consortium). AR mRNA was increased in bipolar disorder, but was unchanged in schizophrenia, relative to controls. AR and 5α-reductase mRNAs were significantly positively correlated in bipolar disorder. AR CAG repeat length was significantly shorter in bipolar disorder relative to schizophrenia. AR mRNA expression was highest in cortical layers IV and V, but no layer-specific diagnostic differences were detected. Together, our results suggest enhanced cortical androgen action in people with bipolar disorder.

Estradiol Fluctuation, Sensitivity to Stress, and Depressive Symptoms in the Menopause Transition: A Pilot Study

The menopause transition is associated with an increased risk of depressed mood. Preliminary evidence suggests that increased sensitivity to psychosocial stress, triggered by exaggerated perimenopausal estradiol fluctuation, may play a role. However, accurately quantifying estradiol fluctuation while minimizing participant burden has posed a methodological challenge in the field. The current pilot project aimed to test the feasibility of capturing perimenopausal estradiol fluctuation via 12 weekly measurements of estrone-3-glucuronide (E1G), a urinary metabolite of estradiol, using participant-collected urine samples in 15 euthymic perimenopausal women ages 45-55 years. Furthermore, it aimed to correlate E1G fluctuation (standard deviation across the 12 E1G measurements) with weekly mood and cardiovascular, salivary cortisol, and subjective emotional responses to the Trier Social Stress Test (TSST) at weeks 4, 8, and 12. Protocol acceptability and adherence was high; furthermore, E1G fluctuation was positively associated with anhedonic depressive symptoms and weekly negative affect. E1G fluctuation was also associated with increased heart rate throughout the TSST as well as higher levels of rejection, anger, and sadness. E1G fluctuation was not significantly associated with TSST blood pressure or cortisol levels. This study suggests a feasible method of assessing estradiol fluctuation in the menopause transition and provides support for the hypothesis that perimenopausal estradiol fluctuation increases sensitivity to psychosocial stress and vulnerability to depressed mood.

Important unanswered questions about adult neurogenesis in schizophrenia

PURPOSE OF REVIEW

Aberrant neurogenesis may contribute to the pathogenesis, pathophysiology and symptoms of schizophrenia. This review summarizes the state of knowledge of adult neurogenesis in schizophrenia and raises important unanswered questions. We highlight how alterations in signalling molecules in the local and peripheral environments in schizophrenia may regulate adult neurogenesis in the human subgranular zone of the hippocampus and the subependymal zone (SEZ).

RECENT FINDINGS

Cell proliferation and density of mature neurons are reduced in the hippocampus, yet the extent of adult neurogenesis remains unexplored in the SEZ in schizophrenia. The human SEZ is a major source of postnatally migrating cortical and striatal inhibitory interneurons, indicating that aberrant neurogenesis may extend to the SEZ and contribute to inhibitory interneuron deficits in schizophrenia. Trophic factors and inflammatory cytokines regulate the generation of new neurons in rodents, suggesting that altered expression of these signalling molecules in the brain, peripheral vasculature and cerebrospinal fluid in schizophrenia may impact adult neurogenesis in both the hippocampus and the SEZ.

SUMMARY

Knowledge about adult neurogenesis remains scant in schizophrenia. We propose that a more rigorous examination of adult neurogenesis in relation to regulatory signalling molecules will allow us to identify how abnormalities may contribute to the pathophysiology of schizophrenia.

Reorganization of Functional Networks in Verbal Working Memory Circuitry in Early Midlife: The Impact of Sex and Menopausal Status

Converging preclinical and human evidence indicates that the decline in ovarian estradiol production during the menopausal transition may play a mechanistic role in the neuronal changes that occur early in the aging process. Here, we present findings from a population-based fMRI study characterizing regional and network-level differences in working memory (WM) circuitry in midlife men and women (N = 142; age range 46-53), as a function of sex and reproductive stage. Reproductive histories and hormonal evaluations were used to determine menopausal status. Participants performed a verbal WM task during fMRI scanning. Results revealed robust differences in task-evoked responses in dorsolateral prefrontal cortex and hippocampus as a function of women's reproductive stage, despite minimal variance in chronological age. Sex differences in regional activity and functional connectivity that were pronounced between men and premenopausal women were diminished for postmenopausal women. Critically, analyzing data without regard to sex or reproductive status obscured group differences in the circuit-level neural strategies associated with successful working memory performance. These findings underscore the importance of reproductive age and hormonal status, over and above chronological age, for understanding sex differences in the aging of memory circuitry. Further, these findings suggest that early changes in working memory circuitry are evident decades before the age range typically targeted in cognitive aging studies.

Considering the role of adolescent sex steroids in schizophrenia

Schizophrenia is a disabling illness that is typically first diagnosed during late adolescence to early adulthood. It has an unremitting course and is often treatment-resistant. Many clinical aspects of the illness suggest that sex steroid-nervous system interactions may contribute to the onset, course of symptoms and the cognitive impairment displayed by men and women with schizophrenia. Here, we discuss the actions of oestrogen and testosterone on the brain during adolescent development and in schizophrenia from the perspective of experimental studies in animals, human post-mortem studies, magnetic resonance imaging studies in living humans and clinical trials of sex steroid-based treatments. We present evidence of potential beneficial, as well as detrimental, effects of both testosterone and oestrogen. We provide a rationale for the necessity to further elucidate sex steroid mechanisms of action at different ages, sexes and brain regions to more fully understand the role of testosterone and oestrogen in the pathophysiology of schizophrenia. The weight of the evidence suggests that sex steroid hormones influence mammalian brain function, including both cognition and emotion, and that pharmaceutical agents aimed at sex steroid receptors appear to provide a novel treatment avenue to reduce symptoms and improve cognition in men and women with schizophrenia.

Steroid and Xenobiotic Receptor Signalling in Apoptosis and Autophagy of the Nervous System

Apoptosis and autophagy are involved in neural development and in the response of the nervous system to a variety of insults. Apoptosis is responsible for cell elimination, whereas autophagy can eliminate the cells or keep them alive, even in conditions lacking trophic factors. Therefore, both processes may function synergistically or antagonistically. Steroid and xenobiotic receptors are regulators of apoptosis and autophagy; however, their actions in various pathologies are complex. In general, the estrogen (ER), progesterone (PR), and mineralocorticoid (MR) receptors mediate anti-apoptotic signalling, whereas the androgen (AR) and glucocorticoid (GR) receptors participate in pro-apoptotic pathways. ER-mediated neuroprotection is attributed to estrogen and selective ER modulators in apoptosis- and autophagy-related neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases, stroke, multiple sclerosis, and retinopathies. PR activation appeared particularly effective in treating traumatic brain and spinal cord injuries and ischemic stroke. Except for in the retina, activated GR is engaged in neuronal cell death, whereas MR signalling appeared to be associated with neuroprotection. In addition to steroid receptors, the aryl hydrocarbon receptor (AHR) mediates the induction and propagation of apoptosis, whereas the peroxisome proliferator-activated receptors (PPARs) inhibit this programmed cell death. Most of the retinoid X receptor-related xenobiotic receptors stimulate apoptotic processes that accompany neural pathologies. Among the possible therapeutic strategies based on targeting apoptosis via steroid and xenobiotic receptors, the most promising are the selective modulators of the ER, AR, AHR, PPARγ agonists, flavonoids, and miRNAs. The prospective therapies to overcome neuronal cell death by targeting autophagy via steroid and xenobiotic receptors are much less recognized.

Raloxifene increases prefrontal activity during emotional inhibition in schizophrenia based on estrogen receptor genotype

People with schizophrenia show decreased prefrontal cortex (PFC) activity during emotional response inhibition, a cognitive process sensitive to hormonal influences. Raloxifene, a selective estrogen receptor modulator, binds estrogen receptor alpha (ESR-α), improves memory, attention and normalizes cortical and hippocampal activity during learning and emotional face recognition in schizophrenia. Here, we tested the extent to which raloxifene restores neuronal activity during emotional response inhibition in schizophrenia. Since genetic variation in estrogen receptor alpha (ESR-1) determines cortical ESR-α production and correlates with cognition, we also predicted that genetic ESR-1 variation would differentially relate to increased cortical activity by raloxifene administration. Thirty people with schizophrenia participated in a thirteen-week randomized, double-blind, placebo-controlled, cross-over adjunctive treatment trial of raloxifene administered at 120mg/day. Effects of raloxifene on brain activation were assessed based on ESR-1 genotype using functional magnetic resonance imaging during emotional word inhibition. Raloxifene increased PFC activity during inhibition of response to negative words and the raloxifene related increased PFC activity was greater in patients homozygous for ESR-1 rs9340799 AA relative to G carriers. Comparison to 23 healthy controls demonstrated that PFC activity of people with schizophrenia receiving raloxifene was more similar to controls than to their own brain activity during placebo. Estrogen receptor modulation by raloxifene restores PFC activity during emotional response inhibition in schizophrenia and ESR-1 genotype predicts degree of increased neural activity in response to raloxifene. While these preliminary results require replication, they suggest the potential for personalized pharmacotherapy using ESR-1 and estrogen receptor targeting compounds in schizophrenia.

Estrogen Signaling as a Therapeutic Target in Neurodevelopmental Disorders

Estrogens, the primary female sex hormones, were originally characterized through their important role in sexual maturation and reproduction. However, recent studies have shown that estrogens play critical roles in a number of brain functions, including cognition, learning and memory, neurodevelopment, and adult neuroplasticity. A number of studies from both clinical as well as preclinical research suggest a protective role of estrogen in neurodevelopmental disorders including autism spectrum disorder (ASD) and schizophrenia. Alterations in the levels of estrogen receptors have been found in subjects with ASD or schizophrenia, and adjunctive estrogen therapy has been shown to be effective in enhancing the treatment of schizophrenia. This review summarizes the findings on the role of estrogen in the pathophysiology of neurodevelopmental disorders with a focus on ASD and schizophrenia. We also discuss the potential of estrogen as a therapeutic target in the above disorders.

Naturally Occurring Changes in Estradiol Concentrations in the Menopause Transition Predict Morning Cortisol and Negative Mood in Perimenopausal Depression

Risk of depression increases considerably during the menopause transition (or perimenopause) - the 5-6 years surrounding the last menstrual period. While the mechanisms underlying this increased risk are unknown, we have hypothesized that excessive estradiol (E2) fluctuation, which accompanies the perimenopause, may be implicated. We have furthermore proposed that dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis may underlie E2 fluctuation's effect on mood. This study examined the relationship between weekly changes in salivary E2, salivary cortisol levels and weekly mood in 30 perimenopausal women recruited to achieve equal numbers of women with current depression, past depression, and no history of depression. Greater weekly increases in E2 were associated with increased cortisol among past and currently depressed women; greater E2 increases were also associated with negative mood among currently depressed women. These findings provide evidence that HPA axis dysregulation, correlated with E2 fluctuation, may be implicated in the pathophysiology of perimenopausal depression.

Potential Role of Oestrogen Modulation in the Treatment of Neurocognitive Deficits in Schizophrenia

Cognitive deficits are prevalent in schizophrenia, and these deficits represent a disabling aspect of the illness for which there are no current effective treatments. Recent work has shown that sex hormone levels correlate with brain activity and cognitive abilities differentially in patients with schizophrenia relative to healthy control groups. There is emerging evidence suggesting that oestrogen-based therapies may be useful in reversing the cognitive deficits associated with schizophrenia. To date, the results from clinical trials using oestrogen-based therapies to reverse cognitive impairment in schizophrenia have shown that the selective oestrogen receptor modulator raloxifene may be useful to improve attention, memory, learning and the associated brain activity in chronically ill men and women with schizophrenia or schizoaffective disorder. While these findings of cognitive enhancement with a selective oestrogen receptor modulator in people with schizophrenia are encouraging, additional studies will be required to replicate the initial results, assess the time frame of treatment effects, identify biomarkers in subsets of patients who may be more likely to optimally respond to treatment, and identify a more precise mechanism of action, which may include anti-inflammatory effects of oestrogen-based treatments.

Adolescent testosterone influences BDNF and TrkB mRNA and neurotrophin-interneuron marker relationships in mammalian frontal cortex

Late adolescence in males is a period of increased susceptibility for the onset of schizophrenia, coinciding with increased circulating testosterone. The cognitive deficits prevalent in schizophrenia may be related to unhealthy cortical interneurons, which are trophically dependent on brain derived neurotrophic factor. We investigated, under conditions of depleted (monkey and rat) and replaced (rat) testosterone over adolescence, changes in gene expression of cortical BDNF and TrkB transcripts and interneuron markers and the relationships between these mRNAs and circulating testosterone. Testosterone removal by gonadectomy reduced gene expression of some BDNF transcripts in monkey and rat frontal cortices and the BDNF mRNA reduction was prevented by testosterone replacement. In rat, testosterone replacement increased the potential for classical TrkB signalling by increasing the full length to truncated TrkB mRNA ratio, whereas in the monkey cortex, circulating testosterone was negatively correlated with the TrkB full length/truncated mRNA ratio. We did not identify changes in interneuron gene expression in monkey frontal cortex in response to gonadectomy, and in rat, we showed that only somatostatin mRNA was decreased by gonadectomy but not restored by testosterone replacement. We identified complex and possibly species-specific, relationships between BDNF/TrkB gene expression and interneuron marker gene expression that appear to be dependent on the presence of testosterone at adolescence in rat and monkey frontal cortices. Taken together, our findings suggest there are dynamic relationships between BDNF/TrkB and interneuron markers that are dependent on the presence of testosterone but that this may not be a straightforward increase in testosterone leading to changes in BDNF/TrkB that contributes to interneuron health.

A Role for Estrogen in Schizophrenia: Clinical and Preclinical Findings

Gender differences in schizophrenia have been extensively researched and it is being increasingly accepted that gonadal steroids are strongly attributed to this phenomenon. Of the various hormones implicated, the estrogen hypothesis has been the most widely researched one and it postulates that estrogen exerts a protective effect by buffering females against the development and severity of the illness. In this review, we comprehensively analyse studies that have investigated the effects of estrogen, in particular 17β-estradiol, in clinical, animal, and molecular research with relevance to schizophrenia. Specifically, we discuss the current evidence on estrogen dysfunction in schizophrenia patients and review the clinical findings on the use of estradiol as an adjunctive treatment in schizophrenia patients. Preclinical research that has used animal models and molecular probes to investigate estradiol's underlying protective mechanisms is also substantially discussed, with particular focus on estradiol's impact on the major neurotransmitter systems implicated in schizophrenia, namely, the dopamine, serotonin, and glutamate systems.

Selective Estrogen Receptor Modulation Increases Hippocampal Activity during Probabilistic Association Learning in Schizophrenia

People with schizophrenia show probabilistic association learning impairment in conjunction with abnormal neural activity. The selective estrogen receptor modulator (SERM) raloxifene preserves neural activity during memory in healthy older men and improves memory in schizophrenia. Here, we tested the extent to which raloxifene modifies neural activity during learning in schizophrenia. Nineteen people with schizophrenia participated in a twelve-week randomized, double-blind, placebo-controlled, cross-over adjunctive treatment trial of the SERM raloxifene administered orally at 120 mg daily to assess brain activity during probabilistic association learning using functional magnetic resonance imaging (fMRI). Raloxifene improved probabilistic association learning and significantly increased fMRI BOLD activity in the hippocampus and parahippocampal gyrus relative to placebo. A separate region of interest confirmatory analysis in 21 patients vs 36 healthy controls showed a positive association between parahippocampal neural activity and learning in patients, but no such relationship in the parahippocampal gyrus of healthy controls. Thus, selective estrogen receptor modulation by raloxifene concurrently increases activity in the parahippocampal gyrus and improves probabilistic association learning in schizophrenia. These results support a role for estrogen receptor modulation of mesial temporal lobe neural activity in the remediation of learning disabilities in both men and women with schizophrenia.

Associations between DNA methylation and schizophrenia-related intermediate phenotypes - a gene set enrichment analysis

Multiple genetic approaches have identified microRNAs as key effectors in psychiatric disorders as they post-transcriptionally regulate expression of thousands of target genes. However, their role in specific psychiatric diseases remains poorly understood. In addition, epigenetic mechanisms such as DNA methylation, which affect the expression of both microRNAs and coding genes, are critical for our understanding of molecular mechanisms in schizophrenia. Using clinical, imaging, genetic, and epigenetic data of 103 patients with schizophrenia and 111 healthy controls of the Mind Clinical Imaging Consortium (MCIC) study of schizophrenia, we conducted gene set enrichment analysis to identify markers for schizophrenia-associated intermediate phenotypes. Genes were ranked based on the correlation between DNA methylation patterns and each phenotype, and then searched for enrichment in 221 predicted microRNA target gene sets. We found the predicted hsa-miR-219a-5p target gene set to be significantly enriched for genes (EPHA4, PKNOX1, ESR1, among others) whose methylation status is correlated with hippocampal volume independent of disease status. Our results were strengthened by significant associations between hsa-miR-219a-5p target gene methylation patterns and hippocampus-related neuropsychological variables. IPA pathway analysis of the respective predicted hsa-miR-219a-5p target genes revealed associated network functions in behavior and developmental disorders. Altered methylation patterns of predicted hsa-miR-219a-5p target genes are associated with a structural aberration of the brain that has been proposed as a possible biomarker for schizophrenia. The (dys)regulation of microRNA target genes by epigenetic mechanisms may confer additional risk for developing psychiatric symptoms. Further study is needed to understand possible interactions between microRNAs and epigenetic changes and their impact on risk for brain-based disorders such as schizophrenia.

Adjunctive raloxifene treatment improves attention and memory in men and women with schizophrenia

There is increasing clinical and molecular evidence for the role of hormones and specifically estrogen and its receptor in schizophrenia. A selective estrogen receptor modulator, raloxifene, stimulates estrogen-like activity in brain and can improve cognition in older adults. The present study tested the extent to which adjunctive raloxifene treatment improved cognition and reduced symptoms in young to middle-age men and women with schizophrenia. Ninety-eight patients with a diagnosis of schizophrenia or schizoaffective disorder were recruited into a dual-site, thirteen-week, randomized, double-blind, placebo-controlled, crossover trial of adjunctive raloxifene treatment in addition to their usual antipsychotic medications. Symptom severity and cognition in the domains of working memory, attention/processing speed, language and verbal memory were assessed at baseline, 6 and 13 weeks. Analyses of the initial 6-week phase of the study using a parallel groups design (with 39 patients receiving placebo and 40 receiving raloxifene) revealed that participants receiving adjunctive raloxifene treatment showed significant improvement relative to placebo in memory and attention/processing speed. There was no reduction in symptom severity with treatment compared with placebo. There were significant carryover effects, suggesting some cognitive benefits are sustained even after raloxifene withdrawal. Analysis of the 13-week crossover data revealed significant improvement with raloxifene only in attention/processing speed. This is the first study to show that daily, oral adjunctive raloxifene treatment at 120 mg per day has beneficial effects on attention/processing speed and memory for both men and women with schizophrenia. Thus, raloxifene may be useful as an adjunctive treatment for cognitive deficits associated with schizophrenia.

Correlation of ERα/ERβ expression with dendritic and behavioural changes in CUMS mice

In response to chronic stress, oestrogen receptor (ER)α acts as an anxiogenic agent as opposed to ERβ which predominantly acts as an anxiolytic agent. These properties of ER play an important role in mediating anxiety- and depression-like behaviour and physiological responses. However, the precise underlying mechanism remains unclear. In particular, not much is known about the expression of ERα and ERβ in the stress-sensitive brain regions such as the prefrontal cortex, hippocampus and amygdala. Using a rodent model of chronic unpredictable mild stress (CUMS), we report that two weeks of CUMS in young male mice (10±2weeks) induces noteworthy changes in the ratio of ERα/ERβ in the prefrontal cortex and hippocampus. While we observed a significant (P<0.05) increase in ERα mRNA and protein expression levels, the expression of ERβ in the prefrontal cortex, hippocampus and amygdala was significantly reduced. This increase in ERα expression with concomitant decrease in ERβ expression was associated with increased anxiety- and depression-like behaviour as observed in elevated plus maze test, open field test, forced swim test and sucrose preference test. In addition to these behavioural changes, we report the decrease of dendritic complexity with concomitant increase in spine density in the medial prefrontal cortex, dorsohippocampal CA3 region and basolateral complex of amygdala (BLA). Taken together, these results suggest that the CUMS-induced increase in the ratio of ERα/ERβ causes dendritic remodeling, which in turn might be responsible for increase in anxiety- and depression-like behaviour in young male mice.

17β-estradiol differentially regulates stress circuitry activity in healthy and depressed women

Many regions within stress neurocircuitry, including the anterior hypothalamus, amygdala, hippocampus, and medial prefrontal cortex, are densely populated with sex steroid receptors. Substantial evidence from animal studies indicates that the gonadal hormone 17β-estradiol (E₂) impacts the structure and function of these regions, but human studies are limited. Characterizing estradiol's role in stress circuitry in vivo in humans may have important clinical implications given the comorbidity between major depressive disorder (MDD), stress circuitry dysfunction and endocrine dysregulation. In this study, we determined estradiol's role in modulating activity within cortical and subcortical stress circuitry regions in healthy and MDD women. Subjects were part of a population-based birth cohort, the New England Family Study. Capitalizing on the endogenous fluctuation in E₂ during the menstrual cycle, we conducted a within-person repeated-measures functional neuroimaging study in which 15 women with recurrent MDD, in remission, and 15 healthy control women underwent hormonal evaluations, behavioral testing, and fMRI scanning on two occasions, under low and high E₂ conditions. Subjects completed an fMRI scan while undergoing a mild visual stress challenge that reliably activated stress neural circuitry. Results demonstrate that E₂ modulates activity across key stress circuitry regions, including bilateral amygdala, hippocampus, and hypothalamus. In healthy women, robust task-evoked BOLD signal changes observed under low E₂ conditions were attenuated under high E₂ conditions. This hormonal capacity to regulate activity in stress circuitry was not observed in MDD women, despite their remitted status, suggesting that dysregulation of gonadal hormone function may be a characteristic trait of the disease. These findings serve to deepen our understanding of estradiol's actions in the healthy brain and the neurobiological mechanisms that may underlie the pronounced sex difference in MDD risk.

Hormone replacement with 17β-estradiol plus dihydrotestosterone restores male sexual behavior in rats treated neonatally with clomipramine

Male sexual behavior (MSB) in rodents, in both its consummatory and motivational components, is regulated by hormones such as testosterone, 17β-estradiol and 5-α-dihydrotestosterone. In experiments, neonatal treatment with clomipramine (CMI; a serotonin reuptake inhibitor) reproduces some of the signs of depression in adult age, including reduced sexual behavior manifested in a lower percentage of subjects that mount, intromit and ejaculate, although their testosterone levels were not altered. However, the effect of this treatment on estrogen levels and the consequences of hormone substitution using 17β-estradiol and 5-α-dihydrotestosterone on the expression of male sexual behavior are still unknown. Therefore, the objective of the present study was to analyze the effect of neonatal treatment with CMI on plasma testosterone and 17β-estradiol levels, and the role of testosterone, 17β-estradiol and 5-α-dihydrotestosterone in altering the consummatory and motivational components of sexual behavior in male rats. To this end, it analyzed the copulatory parameters and sexual incentive motivation (SIM) of rats treated with CMI under two conditions: basal and post-hormone replacements. Neonatal treatment with CMI did not affect plasma testosterone or 17β-estradiol concentrations, but did decrease both the consummatory component and sexual motivation according to the results of the SIM test. These aspects were recovered after administering 17β-estradiol +5-α-dihydrotestosterone, but not testosterone.

Impact of endocrine-disrupting chemicals on neural development and the onset of neurological disorders

Even though high doses of organic pollutants are toxic, relatively low concentrations have been reported to cause long-term alterations in functioning of individual organisms, populations and even next generations. Among these pollutants are dioxins, polychlorinated biphenyls, pesticides, brominated flame retardants, plasticizers (bisphenol A, nonylphenol, and phthalates) as well as personal care products and drugs. In addition to toxic effects, they are able to interfere with hormone receptors, hormone synthesis or hormone conversion. Because these chemicals alter hormone-dependent processes and disrupt functioning of the endocrine glands, they have been classified as endocrine-disrupting chemicals (EDCs). Because certain EDCs are able to alter neural transmission and the formation of neural networks, the term neural-disrupting chemicals has been introduced, thus implicating EDCs in the etiology of neurological disorders. Recently, public concern has been focused on the effects of EDCs on brain function, concomitantly with an increase in neuropsychiatric disorders, including autism, attention deficit and hyperactivity disorder as well as learning disabilities and aggressiveness. Several lines of evidence suggest that exposure to EDCs is associated with depression and could result in neural degeneration. EDCs act via several classes of receptors with the best documented mechanisms being reported for nuclear steroid and xenobiotic receptors. Low doses of EDCs have been postulated to cause incomplete methylation of specific gene regions in the young brain and to impair neural development and brain functions across generations. Efforts are needed to develop systematic epidemiological studies and to investigate the mechanisms of action of EDCs in order to fully understand their effects on wildlife and humans.

Effect of miroestrol on ovariectomy-induced cognitive impairment and lipid peroxidation in mouse brain

Miroestrol (MR) is a phytoestrogen isolated from Pueraria candollei var. mirifica (KwaoKrueaKhao), a Thai medicinal plant used for rejuvenation. We examined the effects of MR on cognitive function, oxidative brain damage, and the expression of genes encoding brain-derived neurotrophic factor (BDNF) and cyclic AMP-responsive element-binding protein (CREB), factors implicated in neurogenesis and synaptic plasticity, in ovariectomized (OVX) mice. OVX decreased serum 17β-estradiol level and uterine weight. OVX also impaired object recognition performance in the novel object recognition test and spatial cognitive performance in the Y-maze test and the water maze test. Daily treatment of MR dose-dependently attenuated OVX-induced cognitive dysfunction. Moreover, OVX mice had a significantly increased level of thiobarbituric acid-reactive substances, and down-regulated expression levels of BDNF and CREB mRNAs in the hippocampus and frontal cortex. MR treatment as well as hormone replacement therapy with 17β-estradiol significantly reversed these neurochemical alterations caused by OVX. These results suggest that MR ameliorates cognitive deficits in OVX animals via attenuation of OVX-induced oxidative stress and down-regulation of BDNF and CREB mRNA transcription in the brain. Our findings raise the possibility that MR and Pueraria candollei var. mirifica, the plant of origin of MR, may have a beneficial effect on cognitive deficits like AD in which menopause/ovariectomy are implicated as risk factors.

Estrogen and memory system bias in females across the lifespan

Studies in both rodents and humans have made much progress in shedding light on how fluctuations in ovarian hormones can affect memory in women across the lifespan. Specifically, advances in neuroscience have identified multiple memory systems that are each mediated by different brain areas. Two memory systems used to navigate an environment are ‘place’ and ‘response’ memory. They are defined as either using an allocentric strategy: using a spatial or cognitive map of the surroundings, or an egocentric strategy: using habitual-turns/movements, respectively. Studies in neuroendocrinology have shown that estrogen levels can bias a female to use one memory system over another to solve a task, such that high estrogen levels are associated with using place memory and low levels with using response memory. Furthermore, recent advances in identifying and localizing estrogen receptors in the rodent brain are uncovering which brain regions are affected by estrogen and providing insight into how hormonal fluctuations during the menstrual cycle, pregnancy, and menopause might affect which memory system is facilitated or impaired in women at different life stages. These studies can help point the way to improving cognitive health in women.

Estrogen receptor α functions in the regulation of motivation and spatial cognition in young male rats

Estrogenic functions in regulating behavioral states such as motivation, mood, anxiety, and cognition are relatively well documented in female humans and animals. In males, however, although the entire enzymatic machinery for producing estradiol and the corresponding receptors are present, estrogenic functions have been largely neglected. Therefore, and as a follow-up study to previous research, we sub-chronically applied a specific estrogen receptor α (ERα) antagonist in young male rats before and during a spatial learning task (holeboard). The male rats showed a dose-dependent increase in motivational, but not cognitive, behavior. The expression of hippocampal steroid receptor genes, such as glucocorticoid (GR), mineralocorticoid (MR), androgen (AR), and the estrogen receptor ERα but not ERβ was dose-dependently reduced. The expression of the aromatase but not the brain-derived neurotrophic factor (BDNF) encoding gene was also suppressed. Reduced gene expression and increased behavioral performance converged at an antagonist concentration of 7.4 µmol. The hippocampal and blood serum hormone levels (corticosterone, testosterone, and 17β-estradiol) did not differ between the experimental groups and controls. We conclude that steroid receptors (and BDNF) act in a concerted, network-like manner to affect behavior and mutual gene expression. Therefore, the isolated view on single receptor types is probably insufficient to explain steroid effects on behavior. The steroid network may keep motivation in homeostasis by supporting and constraining the behavioral expression of motivation.

Serum testosterone levels are related to cognitive function in men with schizophrenia

BACKGROUND

Sex steroids such as oestrogen and testosterone are potent neurodevelopmental hormones that also play a role in neuromodulation and neuroprotection of the mature brain. Sex steroid hormones may also be involved in the pathophysiology of schizophrenia as reduced circulating sex steroid levels and changes in brain sex steroid receptors are found in people with schizophrenia compared to controls. In men with schizophrenia, recent studies have documented an inverse correlation between serum testosterone and negative symptoms. Our study sought to confirm whether men with schizophrenia had lower levels of testosterone relative to controls and to determine whether lower testosterone levels were related to higher symptom severity and impaired cognition.

METHOD

Circulating serum hormone levels (testosterone, oestrogen, and prolactin), cognitive function and symptoms were assessed in 29 chronically ill men with schizophrenia or schizoaffective disorder. Twenty healthy men were recruited as a comparison group. A series of regression analyses were performed to determine the extent to which circulating sex steroid hormone levels predict cognition and symptoms in men with schizophrenia.

RESULTS

We did not find a significant difference in serum testosterone levels between groups. However, circulating testosterone levels significantly predicted performance on verbal memory, processing speed, and working memory in men with schizophrenia. With the exception of an effect of oestrogen on verbal memory, circulating sex steroid levels did not predict cognitive function in healthy men. Testosterone levels were not related to positive or negative symptom severity, but testosterone influenced excitement/hostility levels in our schizophrenia sample.

CONCLUSIONS

The results suggest that circulating sex steroids may modulate cognitive deficits associated with schizophrenia.

Blockade of estrogen by hormonal contraceptives impairs fear extinction in female rats and women

BACKGROUND

Fear extinction is a laboratory model of fear inhibition and is the basis of exposure therapy for anxiety disorders. Emerging evidence from naturally cycling female rodents and women indicates that estrogens are necessary to the consolidation of fear extinction. Hormonal contraceptives (HCs) inhibit estrogen production; yet, their effects on fear extinction are unknown.

METHODS

We used a cross-species translational approach to investigate the impact of HCs and estradiol supplementation on fear extinction in healthy women (n=76) and female rats (n = 140).

RESULTS

Women using HCs exhibited significantly poorer extinction recall compared with naturally cycling women. The extinction impairment was also apparent in HC-treated female rats and was associated with reduced serum estradiol levels. The impairment could be rescued in HC-treated rats either by terminating HC treatment after fear learning or by systemic injection of estrogen-receptor agonists before fear extinction, all of which restored serum estradiol levels. Finally, a single administration of estradiol to naturally cycling women significantly enhanced their ability to recall extinction memories.

CONCLUSIONS

Together, these findings suggest that HCs may impact women's ability to inhibit fear but that this impairment is not permanent and could potentially be alleviated with estrogen treatment.

Moderation of Breastfeeding Effects on Adult Depression by Estrogen Receptor Gene Polymorphism

Breastfeeding is known to benefit both the mother’s and the child’s health. Our aim was to test the interactive effects between estrogen receptor 1 (ESR1) rs2234693 and breastfeeding when predicting the child’s later depression in adulthood. A sample of 1209 boys and girls from the Young Finns Study were followed from childhood over 27 years up to age 30–45 years. Adulthood depressive symptoms were self-reported by the participants using the Beck Depression Inventory. Breastfeeding as well as several possibly confounding factors was reported by the parents in childhood or adolescence. Breastfeeding tended to predict lower adult depression, while ESR1 rs2234693 was not associated with depression. A significant interaction between breastfeeding and ESR1 was found to predict participants’ depression (P=.004) so that C/C genotype carriers who had not been breastfed had higher risk of depression than T-allele carriers (40.5% versus 13.0%) while there were no genotypic differences among those who had been breastfed. In sex-specific analysis, this interaction was evident only among women. We conclude that child’s genes and maternal behavior may interact in the development of child’s adult depression so that breastfeeding may buffer the inherited depression risk possibly associated with the C/C genotype of the ESR1 gene.

Sex steroids and schizophrenia

The peak in incidence for schizophrenia is during late adolescence for both sexes, but within this time frame the peak is both earlier and steeper for males. Additionally, women have a second peak in incidence following menopause. Two meta-analyses have reported that men have an overall ∼40% greater chance of developing schizophrenia than do women (Aleman et al., 2003; McGrath et al., 2004). These and other findings have led to the suggestion that ovarian hormones may be protective against schizophrenia. Less explored is the potential role of testosterone in schizophrenia, although disruptions in steroid levels have also been reported in men with the illness. The relationship between increased gonadal hormone release per se and peri-adolescent vulnerability for psychiatric illness is difficult to tease apart from other potentially contributory factors in clinical studies, as adolescence is a turbulent period characterized by many social and biological changes. Despite the obvious opportunity provided by animal research, surprisingly little basic science effort has been devoted to this important issue. On the other hand, the animal work offers an understanding of the many ways in which gonadal steroids exert a powerful impact on the brain, both shaping its development and modifying its function during adulthood. Recently, investigators using preclinical models have described a greater male vulnerability to neurodevelopmental insults that are associated with schizophrenia; such studies may provide clinically relevant insights into the role of gonadal steroids in psychiatric illness.