Reproductive aging, sex steroids, and mood disorders

Impact of Menopause in Patients with Multiple Sclerosis: Current Perspectives

Given the aging population, with a peak age-specific prevalence that is shifting beyond the age of 50, several women currently living with MS are very close to menopause. Menopause is usually characterized by several specific symptoms with adverse impacts on different aspects of a woman's quality of life, such as fatigue, and cognitive, mood and bladder disorders, which overlap with symptoms of MS. Generally, after this biological transition, women with MS appear to be subject to less inflammatory activity. However, several studies have reported an increase of disability accumulation after menopause, suggesting that it is a turning point to a more progressive phase of the disease. This may be attributable to the hormonal and immunological changes associated with menopause, with several effects on neuroinflammation and neurodegeneration increasing due to the immunosenescence of aging. This review summarizes the hormonal and immunological changes associated with menopause, detailing the effects on MS symptoms, outcomes, and the aging process. Furthermore, possible interventions to improve patients' quality of life are evaluated. In fact, it is increasingly necessary to improve the global management of MS women, as well as their lives, at this multifaceted turning point.

Sex-specific Effects of Endocrine-disrupting Chemicals on Brain Monoamines and Cognitive Behavior

The period of brain sexual differentiation is characterized by the development of hormone-sensitive neural circuits that govern the subsequent presentation of sexually dimorphic behavior in adulthood. Perturbations of hormones by endocrine-disrupting chemicals (EDCs) during this developmental period interfere with an organism's endocrine function and can disrupt the normative organization of male- or female-typical neural circuitry. This is well characterized for reproductive and social behaviors and their underlying circuitry in the hypothalamus and other limbic regions of the brain; however, cognitive behaviors are also sexually dimorphic, with their underlying neural circuitry potentially vulnerable to EDC exposure during critical periods of brain development. This review provides recent evidence for sex-specific changes to the brain's monoaminergic systems (dopamine, serotonin, norepinephrine) after developmental EDC exposure and relates these outcomes to sex differences in cognition such as affective, attentional, and learning/memory behaviors.

Depressive subfactors and cognitive function in midlife

BACKGROUND

This study aimed to evaluate the heterogeneous association of depressive subtypes with cognitive function, according to age and sex.

METHODS

This cross-sectional study utilized the baseline data from the Cardiovascular and Metabolic Disease Etiology Research Center cohort and included 5271 midlife participants. For identifying depressive subtypes of the Beck Depression Inventory Ⅱ items, factor analyses were utilized and yielded two factors -melancholic- and somatic-depressive subtypes. The information of Mini-Mental State Examination was used for screening cognitive function. The association between depressive subtypes and cognitive function was analysed using multiple regression after adjusting for all covariates.

RESULTS

We observed heterogeneous association between depressive subtypes and cognitive dysfunction in midlife participants. The results of sex- and age- stratified analyses indicated that the somatic subtype was associated with dysfunction in cognitive ability. Among women, especially those aged over 60 years, MMSE scores decreased as the somatic depression scores increased. These results might suggest that the somatic subtype, rather than the melancholic subtype, has a greater association with cognitive assessment in a general midlife population, particularly older women.

LIMITATIONS

Although a confirmatory factor analysis was performed, depressive subtypes need validation and reliability tests.

CONCLUSIONS

Given this heterogeneity, characterisation of depressive subtypes according to sex and age may improve our understanding of how each depressive symptom is associated differently with cognitive dysfunction in midlife.

Menopause and multiple sclerosis: Influence on prognosis and role of disease-modifying drugs and hormonal replacement therapy

Background:

Sex hormones play a role in both the risk and the prognosis of multiple sclerosis (MS). Considering all stages of women’s reproductive life, data regarding the influence of menopause on MS and vice versa are scarce.

Objective:

The aim of this study was to review the evidence addressing the relationship between menopause and MS.

Methods:

A literature search through PubMed was conducted, selecting studies that assessed (1) the influence of menopause in the MS course, (2) the influence of MS and disease-modifying drugs (DMD) on the development of menopause and (3) the effect of hormone replacement therapy (HRT) on symptoms of menopausal MS patients.

Results:

(1) Most studies suggest menopause may transitorily aggravate MS symptoms. Two studies found an inflexion point on the Expanding Disability Status Scale (EDSS) with clinical worsening during the menopausal transition. Another study considering full EDSS trajectories from clinically isolated syndrome to postmenopause did not find such an EDSS inflection; (2) MS and DMD do not seem to alter the age of menopause onset; and (3) HRT in menopausal MS patients has not shown consistent benefits.

Conclusion:

Menopause seems to be associated with transient symptom worsening, but the existence of an inflection in disability progression is still controversial. Properly designed studies are necessary to achieve conclusive results.

The Swiss Perimenopause Study - study protocol of a longitudinal prospective study in perimenopausal women

BACKGROUND

The perimenopause is associated with considerable biopsychosocial changes. The majority of women manage to adjust to these changes and cope well with the shift from reproductive to non-reproductive life. However, some women develop burdensome physical and psychological symptoms during the perimenopause. A strong link between menopausal complaints and depressed mood has been shown in this regard. To date, the decisive factors determining whether a woman will successfully achieve a healthy transition remain unclear. Thus, the purpose of this study is to investigate a range of theory-based markers related to health in perimenopausal women.

METHODS

The Swiss Perimenopause Study comprises a sample of 135 healthy perimenopausal women aged 40-56. A variety of health-related genetic, epigenetic, endocrinological, physiological, and psychosocial markers associated with the menopausal transition are investigated over a period of 13 months.

DISCUSSION

The Swiss Perimenopause Study will contribute to a better understanding of the biopsychosocial processes associated with the perimenopause, which should help to improve the clinical care of women undergoing the menopausal transition.

Depression during perimenopause: the role of the obstetrician-gynecologist

Depression in women is more common during perimenopause (the transition to menopause) than at other times in the life cycle. Symptoms of depression may be different in perimenopausal women compared to younger or older women, and are often dismissed as part of normal menopause. This is an expert narrative review. There are several evidence-based screening modalities which can be integrated into routine women's health visits, and can facilitate distinguishing between depression and normal perimenopausal symptoms. There is emerging evidence regarding the effect of hormonal changes on the development of perimenopausal depression and its optimal treatment, though critical research gaps remain. Obstetrician-gynecologists and other primary care providers play a vital role in the detection and management of depression in women. Providers caring for women during perimenopause have a unique opportunity to diagnose depression in their patients and identify appropriate treatment options.

Guidelines for the evaluation and treatment of perimenopausal depression: summary and recommendations

There is a new appreciation of the perimenopause - defined as the early and late menopause transition stages as well as the early postmenopause - as a window of vulnerability for the development of both depressive symptoms and major depressive episodes. However, clinical recommendations on how to identify, characterize and treat clinical depression are lacking. To address this gap, an expert panel was convened to systematically review the published literature and develop guidelines on the evaluation and management of perimenopausal depression. The areas addressed included: 1) epidemiology; 2) clinical presentation; 3) therapeutic effects of antidepressants; 4) effects of hormone therapy; and 5) efficacy of other therapies (eg, psychotherapy, exercise, and natural health products). Overall, evidence generally suggests that most midlife women who experience a major depressive episode during the perimenopause have experienced a prior episode of depression. Midlife depression presents with classic depressive symptoms commonly in combination with menopause symptoms (ie, vasomotor symptoms, sleep disturbance), and psychosocial challenges. Menopause symptoms complicate, co-occur, and overlap with the presentation of depression. Diagnosis involves identification of menopausal stage, assessment of co-occurring psychiatric and menopause symptoms, appreciation of the psychosocial factors common in midlife, differential diagnoses, and the use of validated screening instruments. Proven therapeutic options for depression (ie, antidepressants, psychotherapy) are the front-line treatments for perimenopausal depression. Although estrogen therapy is not approved to treat perimenopausal depression, there is evidence that it has antidepressant effects in perimenopausal women, particularly those with concomitant vasomotor symptoms. Data on estrogen plus progestin are sparse and inconclusive.

Modulating Effects of Cholecalciferol Treatment on Estrogen Deficiency-Induced Anxiety-Like Behavior of Adult Female Rats

BACKGROUND

Vitamin D can be one of the candidate substances that are used as additional supplementation in the treatment of anxiety-related disorders in women with estrogen imbalance.

MATERIALS AND METHODS

The aim of the present study was to examine the effects of chronic cholecalciferol administration (1.0, 2.5 or 5.0 mg/kg/day, s.c.) on the anxiety-like behavior and monoamines levels in the rat hippocampus following ovariectomy in female rats. Cholecalciferol was given to ovariectomized (OVX) rats and OVX rats treated with 17β-estradiol (17β-E2, 0.5 μg/rat, s.c.). The anxiety-like behavior was assessed in the elevated plus maze (EPM) and the light-dark tests (LDT), locomotor and grooming activities were assessed in the open-field test (OFT).

RESULTS

Cholecalciferol in high doses alone or in combination with 17β-E2-induced anxiolytic-like effects in OVX and OVX rats treated with 17β-E2 as evidenced in the EPM and LDT tests, and increased grooming activity in the OFT test. We found that DA and 5-HT levels increased while 5-HT turnover in the hippocampus decreased in these groups of OVX rats.

CONCLUSION

Our results indicate that cholecalciferol in high doses has a marked anxiolytic-like effect due to an increase in the monoamines levels in the experimental rat model of estrogen deficiency.

Serotonin-estrogen interactions: What can we learn from pregnancy?

We have reviewed the scientific literature related to four diseases in which to serotonin (5-HT) is involved in the etiology, herein named 5-HT-linked diseases, and whose prevalence is influenced by estrogenic status: depression, migraine, irritable bowel syndrome and eating disorders. These diseases all have in common a sex-dimorphic prevalence, with women more frequently affected than men. The co-occurrence between these 5-HT-linked diseases suggests that they have common physiopathological mechanisms. In most 5-HT-linked diseases (except for anorexia nervosa and irritable bowel syndrome), a decrease in the serotonergic tone is observed and estrogens are thought to contribute to the improvement of symptoms by stimulating the serotonergic system. Human pregnancy is characterized by a unique 5-HT and estrogen synthesis by the placenta. Pregnancy-specific disorders, such as hyperemesis gravidarum, gestational diabetes mellitus and pre-eclampsia, are associated with a hyperserotonergic state and decreased estrogen levels. Fetal programming of 5-HT-linked diseases is a complex phenomenon that involves notably fetal-sex differences, which suggest the implication of sex steroids. From a mechanistic point of view, we hypothesize that estrogens regulate the serotonergic system, resulting in a protective effect against 5-HT-linked diseases, but that, in turn, 5-HT affects estrogen synthesis in an attempt to retrieve homeostasis. These two processes (5-HT and estrogen biosynthesis) are crucial for successful pregnancy outcomes, and thus, a disruption of this 5-HT-estrogen relationship may explain pregnancy-specific pathologies or pregnancy complications associated with 5-HT-linked diseases.

The role of family history of depression and the menopausal transition in the development of major depression in midlife women: Study of women's health across the nation mental health study (SWAN MHS)

BACKGROUND

This study evaluated whether family history of depression predicts major depression in midlife women above and beyond static risk factors (such as personal history of depression prior to midlife) and risks that may change dynamically across midlife (such as menopausal, psychosocial, and health profiles).

METHODS

Participants were 303 African American and Caucasian women (42-52 years at baseline) recruited into the Study of Women's Health across the Nation (SWAN) Mental Health Study (MHS) in Pittsburgh. Major depression was assessed annually with Structured Clinical Interviews for DSM-IV. Family mental health history was collected at the ninth or tenth annual follow-up. Random effects logistic regression was used to assess the relationship between family history of depression and midlife depression, controlling for baseline sociodemographic characteristics and time-varying risk factors.

RESULTS

Family history of depression was associated with midlife depression after adjusting for participant's history of major depression prior to midlife, trait anxiety and baseline age, and time-varying menopausal status, body mass index, very upsetting life events, and chronic difficulties (OR = 2.24, 95% CI = 1.17-4.29, P = .02). Higher odds of major depression were found when women were late perimenopausal or postmenopausal relative to when they were premenopausal or early perimenopausal (OR = 3.01, 95% CI = 1.76-5.15, P < .0001). However, menopausal status was only associated with major depression among women without a family history.

CONCLUSIONS

Family history of depression predicts major depression in midlife women independent of the menopausal transition and other time-varying covariates. Notably, the menopausal transition was associated with increased risk only among women without a family history of depression.

Review: Puberty as a time of remodeling the adult response to ovarian hormones

During pubertal development, an animal's response to stress changes and sexual differentiation of the brain and behavior continue. We discovered that particular stressors, such as shipping from suppliers or an immune challenge with lipopolysaccharide, during the prolonged pubertal period of female mice result in long-term changes in behavioral responsiveness of the brain to estradiol assessed in adulthood. All behaviors influenced by estradiol and/or progesterone that we have studied are compromised by a stressor during pubertal development. Depending on the behavior, immune challenge or shipping from suppliers during pubertal development decreases, eliminates, or even reverses the effects of estradiol. Shipping during this period causes changes in the number of estrogen receptor-immunoreactive cells in key brain areas suggesting one cellular mechanism for this remodeling of the brain's response to hormones. We suggest that particular adverse experiences in girls may cause long-term alterations in the brain's response to estradiol and/or progesterone via activation of the immune system. This in turn could lead to an alteration in any aspect of mental health that is influenced by estradiol.

Is menopausal status related to women's attitudes toward menopause and aging?

The objective of this study was to explore the relationship between menopausal status and attitudes toward menopause and aging. We identified 1,400 Bengali Hindu women aged 40-55 years (early perimenopausal n = 445; late perimenopausal n = 240; early postmenopausal n = 285; late postmenopausal n = 430) from West Bengal, India. Information on attitudes toward menopause and aging was collected from March 2009 to July 2012 using ten agree/disagree statements, of which three were positive, four were negative, and the rest were neutral. We used only the positive and negative statements in the analyses. The participants were given three response options for each statement: (1) agreed, (2) disagreed, and (3) felt neutral. Agreement with positive statements and disagreement with negative statements were scored as 3. The converse responses were scored as 1. Neutral responses were not scored. Thus, the total attitude score for each participant ranged from 7 to 21. Additionally, data on sociodemographic and reproductive variables, menopausal symptoms, and perceptions toward menopause were also collected. Multivariable analyses (ANCOVA) showed that postmenopausal women had more positive attitudes toward menopause and aging than perimenopausal women. Providing balanced information about menopause and aging might help to foster positive attitudes toward menopause.

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.

Regulation of the mouse medial prefrontal cortical synapses by endogenous estradiol

Recent studies suggest that low endogenous estradiol might be a susceptibility factor for anxiety and trauma-related disorders in women. Consistently, fear extinction, a form of inhibitory learning critical for the management of anxiety symptoms, is positively correlated with endogenous estradiol levels. To understand the synaptic basis of the effect of endogenous estradiol on fear extinction, we studied glutamatergic transmission and plasticity in the infralimbic medial prefrontal cortex (IL-mPFC), a brain region crucial for the regulation of fear extinction. Diestrus mice (low estradiol) exhibited a higher basal glutamatergic transmission compared with proestrus mice (high estradiol). Synaptic plasticity was also regulated by endogenous estradiol, which favored synaptic potentiation in a GluN2B-dependent manner. Activation of estrogen receptor β (ERβ) but not ERα rescued synaptic potentiation in diestrus mice by enhancing GluN2B-mediated NMDA receptor transmission. Our results suggest that both endogenous estradiol and ERβ activation facilitate the ability of the IL-mPFC synapses to undergo potentiation, a mechanism necessary for the regulation of fear extinction.

Depressive symptoms in the transition to menopause: the roles of irritability, personality vulnerability, and self-regulation

Although the transition to menopause represents a period of risk for depressive symptoms, there is little research into personality or trait-like factors that may confer vulnerability to depression during the transition to menopause. This study investigated whether the personality trait of self-criticism moderated the effects of irritability on depressive symptoms in women transitioning to menopause and whether these effects were mediated by lower levels of emotional regulation. Participants were 376 women, of whom 157 had entered the transition phase to menopause. These women in the transition phase completed measures of self-criticism, irritable mood, emotional regulation, and depressive symptoms. All analyses controlled for attitudes toward menopause and somatic symptoms. Moderated mediation regression analyses showed that higher levels of irritability were associated with poorer emotional regulation in highly self-critical women, but not in less self-critical women, and poorer emotional regulation was, in turn, related to higher levels depressive symptoms. Findings suggest that the transition to menopause may represent an especially vulnerable period for women with high levels of self-criticism. Although irritability is transitory for most women, for women who are highly self-critical, irritability may tax their ability to self-regulate and lead to more encompassing symptoms of depression.

Effects of SCH-23390 in combination with a low dose of 17β-estradiol on anxiety-like behavior in ovariectomized rats

The aim of this study was to explore effects on anxiety-like behavior of D₁ dopamine receptor agonist, SKF-38393, and of D₁ dopamine receptor antagonist, SCH-23390, given alone or in combination with a low dose of 17β-estradiol (17β-E₂) to ovariectomized (OVX) rats. Two weeks after surgery, OVX rats began 14 days of treatment with the vehicle, a low dose of 17β-E₂ (5.0 μg/rat, s.c.), SKF-38393 (0.1 mg/kg, i.p.), SCH-23390 (0.1 mg/kg, i.p.), SKF-38393 plus 17β-E₂, or SCH-23390 plus 17β-E₂. The animals were tested in the black and white model (BWM) and the open field test (OFT). SCH-23390 (0.1 mg/kg, i.p.) alone or in a combination with a low dose of 17β-E₂ (5.0 μg/rat, s.c.) resulted in anxiolytic-like effect in OVX rats in the BWM. Repeated treatment with SCH-23390 and 17β-E₂ profoundly increased anxiolytic-like effect of single substances exerted per se. Coadministration of SCH-23390 with 17β-E₂ increased frequency of rearing and grooming in OVX rats in OFT. SKF-38393 (0.1 mg/kg, i.p.) treatment failed to alter anxiety-like behavior in OVX rats in the BWM. The results of the present study suggest that 17β-E₂ and SCH-23390 interact to exert anxiolytic-like action and that each of these drugs can potentiate effects of each other.

Associations between psychological well-being, mental health, and hormone therapy in perimenopausal and postmenopausal women: results of two population-based studies

OBJECTIVE

A proportion of women experience depressive and anxiety symptoms and/or disorders in connection with the menopausal transition. Estrogen-only therapy has been reported to have beneficial effects on mental health, but the effects of combined hormone therapy (HT) on mental health are less clear. We studied the associations between HT use and psychopathology in perimenopausal and postmenopausal women.

METHODS

Data on women who participated in the Health 2000 Survey and the National FINRISK Surveys in Finland were analyzed.

RESULTS

An association between current HT use and psychiatric diagnosis in the previous 12 months was found. In addition, HT use was associated with recent self-reported diagnosis of depression and with depressed mood (FINRISK), as well as with major depressive disorder and anxiety disorder (Health 2000). Associations with the following symptoms were found: nervousness, frightening thoughts, nightmares, and headache (FINRISK), feelings of depression (FINRISK and Health 2000), and unhappiness (Health 2000). No differences between different routes of administration or types of HT emerged.

CONCLUSIONS

Current use of HT in perimenopausal and postmenopausal women is associated with worse psychological well-being and mental health than in women not using HT. It is important to identify women in need of psychiatric support at the time of the menopausal transition.

Menopause in multiple sclerosis: therapeutic considerations

While the onset of multiple sclerosis (MS) typically occurs during the childbearing years, many women living with MS are of perimenopausal age. There is frequent overlap between menopausal and MS-related symptoms and co-morbidities (e.g. sexual dysfunction, mood disorders and bladder function). Furthermore, some MS symptoms may be exacerbated by perimenopausal changes such as hot flashes or sleep disturbance. The MS neurologist may frequently be the first to become aware of these symptoms and to play a role in monitoring and managing them. In this review, we describe immunological and neurologic changes at menopause as they may impact MS. We then review common symptoms, including fatigue, depression, sexual function, pain and insomnia, and provide both behavioral and pharmacological suggestions for their management. Next, we discuss the need for osteoporosis and cancer screening in perimenopausal women with MS. Finally, we highlight important research gaps, including what effect, if any, the menopausal transition may play on MS disease course as well as the potential modulatory role of hormone replacement therapies.

Enduring influence of pubertal stressors on behavioral response to hormones in female mice

This article is part of a Special Issue "Puberty and Adolescence". The pubertal period is a time of change in an animal's response to stress, and it is a second period of sexual differentiation of the brain. Recently, it was discovered that particular stressors during the prolonged pubertal period of female mice result in enduring changes in behavioral responsiveness of the brain to estradiol and progesterone. Depending on the behavior, pubertal immune challenge or shipping from suppliers may decrease, eliminate, or even reverse the effects of estradiol. Pubertal immune challenge results in changes in the number of estrogen receptor-immunoreactive cells in key brain areas suggesting a cellular mechanism for this remodeling of the brain's response to hormones. A hypothesis is put forward that predicts that particular adverse experiences in girls may cause long-term alterations in the brain's response to estradiol and/or progesterone via activation of the immune system. This could lead to mood disorders or altered response to any behavior influenced by estradiol in humans.

Synaptic regulation of affective behaviors; role of BDNF

Brain derived neurotrophic factor (BDNF), a neurotrophin essential for nervous system development and synaptic plasticity, has been found to have a significant influence on affective behaviors. The notion that an impairment in BDNF signaling might be involved in affective disorders is originated primarily from the opposing effects of antidepressants and stress on BDNF signaling. Antidepressants enhance BDNF signaling and synaptic plasticity. On the other hand, negative environmental factors such as severe stress suppress BDNF signaling, impair synaptic activity and increase susceptibility to affective disorders. Postmortem studies provided strong support for decreased BDNF signaling in depressive disorders. Remarkably, studies in humans with a single nucleotide polymorphism in the BDNF gene, the BDNF Val66Met which affects regulated release of BDNF, showed profound deficits in hippocampal and prefrontal cortical (PFC) plasticity and cognitive behaviors. BDNF regulates synaptic mechanisms responsible for various cognitive processes including attenuation of aversive memories, a key process in the regulation of affective behaviors. The unique role of BDNF in cognitive and affective behaviors suggests that cognitive deficits due to altered BDNF signaling might underlie affective disorders. Understanding how BDNF modulates synapses in neural circuits relevant to affective behaviors, particularly the medial prefrontal cortical (mPFC)-hippocampus-amygdala pathway, and its interaction with development, sex, and environmental risk factors might shed light on potential therapeutic targets for affective disorders. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.

Effects of social housing on hippocampal dendrites and behavior in ovariectomized rats

Social stress is both species and gender specific. For female rats, individual housing and social instability housing conditions are associated with behavioral indicators of stress and depression. The present study directly compared the effects of six weeks of individual housing, social instability and mixed sex, semi-crowded housing in a visible burrow system (VBS) on ovariectomized female rats. Paired, stable housing was used as the control. Behavioral tests were conducted two, four and six weeks into the housing manipulations and included sucrose consumption, social interest, and activity in the open field. Following a series of four behavioral tests, animals were sacrificed and brains were processed for Golgi impregnation. Basal dendrites of CA3 hippocampal neurons were measured. Results indicate that the individual housing and social instability groups were comparable to the control group for all measures. In contrast, the rats housed in the VBS exhibited reduced activity in open field testing, and alterations in social interest. Dendritic lengths were also reduced in those animals living in the VBS in comparison to the animals housed in pairs. To our knowledge, this is the first report of behavioral and neural effects of VBS housing on female rats. Further research is necessary to determine what facets of the VBS housing are responsible for the behavioral and neural changes. This article is part of a Special Issue entitled 'Animal Models'.

Sex differences, gonadal hormones and the fear extinction network: implications for anxiety disorders

Convergent data from rodents and human studies have led to the development of models describing the neural mechanisms of fear extinction. Key components of the now well-characterized fear extinction network include the amygdala, hippocampus, and medial prefrontal cortical regions. These models are fueling novel hypotheses that are currently being tested with much refined experimental tools to examine the interactions within this network. Lagging far behind, however, is the examination of sex differences in this network and how sex hormones influence the functional activity and reactivity of these brain regions in the context of fear inhibition. Indeed, there is a large body of literature suggesting that sex hormones, such as estrogen, do modulate neural plasticity within the fear extinction network, especially in the hippocampus.After a brief overview of the fear extinction network, we summarize what is currently known about sex differences in fear extinction and the influence of gonadal hormones on the fear extinction network. We then go on to propose possible mechanisms by which sex hormones, such as estrogen, may influence neural plasticity within the fear extinction network. We end with a discussion of how knowledge to be gained from developing this line of research may have significant ramifications towards the etiology, epidemiology and treatment of anxiety disorders.

Higher DHEA-S (dehydroepiandrosterone sulfate) levels are associated with depressive symptoms during the menopausal transition: results from the PENN Ovarian Aging Study

The influence of sex hormones on mood during the menopausal transition has been the subject of ongoing investigation. Because dehydroepiandrosterone sulfate (DHEA-S) has been associated with several indicators of healthy aging, we conducted a population-based study of midlife women to determine the relationship between DHEA-S levels and depressive symptoms and major depression during the transition through menopause. Unexpectedly, the original report revealed a positive correlation between DHEA-S levels and depressive symptoms at baseline. The cohort was studied over 11 years to determine whether the positive association between DHEA-S levels and depression persists through the menopausal transition. We conducted a longitudinal cohort study with 11 assessments during an 11-year interval in Philadelphia, Pennsylvania, using a randomly identified, population-based sample of 436 African American and Caucasian premenopausal women aged 35 to 47 years at enrollment. For outcome measures, we used the Center for Epidemiologic Studies Depression Scale and standardized diagnosis of major depression. In a multivariable model, DHEA-S levels were positively associated with depressive symptoms when adjusted for age, menopausal stage, race, smoking status, and body mass index. There was no association between DHEA-S levels and a diagnosis of major depression. DHEA-S levels were positively associated with depressive symptoms through the menopausal transition. No association with major depression was apparent during the menopausal transition, but results may have limited power due to low prevalence of major depression in this cohort. These findings suggest that taking DHEA supplements may increase depressive symptoms for some women, and women and their physicians should be cautious about instituting DHEA replacement therapy during the menopausal transition.

Accelerated ovarian failure: a novel, chemically induced animal model of menopause

Current rodent models of menopause fail to adequately recapitulate the menopause transition. The intact aging model fails to achieve very low estrogen levels, and the ovariectomy model lacks a perimenopause phase. A new rodent model of accelerated ovarian failure (AOF) successfully replicates human perimenopause and postmenopause, including estrous acyclicity and fluctuating, followed by undetectable, estrogen levels, and allows for the dissociation of the effects of hormone levels from the effects of aging. In this model, an ovotoxic chemical, 4-vinylcyclohexene diepoxide (VCD), selective for primary and primordial follicles, is injected intraperitonelly in animals for 15 days. As the mature follicle population is depleted through natural cycling, ovarian failure follows increasing periods of acyclity. Administered at low doses, VCD specifically causes apoptotic cell death of primordial follicles but does not affect other peripheral tissues, including the liver and spleen, nor does it affect brain inflammation markers. In addition to reducing confounds associated with genetic and surgical manipulations, the AOF model maintains the presence of ovarian tissue which importantly parallels to the menopause transition in humans. The VCD injection procedure can be applied to studies using transgenic or knockout mice strains, or in other disease-state models (e.g., ischemia, atherosclerosis, or diabetes). This AOF model of menopause will generate new insights into women's health particularly in determining the critical periods (i.e., a window of opportunity) during perimenopause for restoring ovarian hormones for the most efficacious effect on memory and mood disorders as well as other menopausal symptoms.

Reproductive aging, menopause, and health outcomes

Changes in ovarian hormone production may affect numerous health outcomes including vasomotor symptoms, cardiovascular disease (CVD), osteoporosis, cognition, depression, mood disorders, sexual function, and vaginal atrophy. We will compare age-related changes to those associated with reproductive aging and menopause and the effects of estrogen therapy on selected health outcomes. Hormone therapy (HT) reduces frequency and severity of hot flashes, prevents bone loss and osteoporotic fractures, and relieves vaginal atrophy. Nonhormone therapy trials with antidepressants or gabapentin for hot flash relief are promising. To date, clinical trial data are insufficient to recommend the use of HT for prevention or treatment of CVD, mood disorders, cognition, or sleep disorders. For some disease states, such as CVD and cognition, a "critical time window" has been proposed but not proven, such that estrogen use early in the menopause transition may be beneficial while estrogen use later in life would lead to increased health risks.

Estrogen therapy and cognition: a review of the cholinergic hypothesis

The pros and cons of estrogen therapy for use in postmenopausal women continue to be a major topic of debate in women's health. Much of this debate focuses on the potential benefits vs. harm of estrogen therapy on the brain and the risks for cognitive impairment associated with aging and Alzheimer's disease. Many animal and human studies suggest that estrogens can have significant beneficial effects on brain aging and cognition and reduce the risk of Alzheimer's-related dementia; however, others disagree. Important discoveries have been made, and hypotheses have emerged that may explain some of the inconsistencies. This review focuses on the cholinergic hypothesis, specifically on evidence that beneficial effects of estrogens on brain aging and cognition are related to interactions with cholinergic projections emanating from the basal forebrain. These cholinergic projections play an important role in learning and attentional processes, and their function is known to decline with advanced age and in association with Alzheimer's disease. Evidence suggests that many of the effects of estrogens on neuronal plasticity and function and cognitive performance are related to or rely upon interactions with these cholinergic projections; however, studies also suggest that the effectiveness of estrogen therapy decreases with age and time after loss of ovarian function. We propose a model in which deficits in basal forebrain cholinergic function contribute to age-related changes in the response to estrogen therapy. Based on this model, we propose that cholinergic-enhancing drugs, used in combination with an appropriate estrogen-containing drug regimen, may be a viable therapeutic strategy for use in older postmenopausal women with early evidence of mild cognitive decline.