Raloxifene and/or estradiol decrease anxiety-like and depressive-like behavior, whereas only estradiol increases carcinogen-induced tumorigenesis and uterine proliferation among ovariectomized rats

The short-term effects of estradiol, raloxifene, and a phytoestrogen in women with perimenopausal depression

OBJECTIVE

We examined the short-term efficacies of three estrogen-like compounds under placebo-controlled conditions in women with perimenopause-related depression (PMD).

METHODS

Women with PMD were randomized in a double-blind parallel design to one of four treatments: transdermal 17-beta estradiol (TE) (100 mcg/d); oral raloxifene (60 mg/d); a proprietary phytoestrogen compound, Rimostil (1,000 mg twice/d); or placebo for 8 weeks. The main outcome measures were the Center for Epidemiology Studies Depression Scale, 17-item Hamilton Rating Scale for Depression (HRSD), and the Beck Depression Inventory completed at each clinic visit. Secondary outcomes included a visual analogue self-rating completed at each clinic visit, and daily self-ratings of hot flush severity. Cognitive tests were performed at pretreatment baseline and at the end of the trial. In the primary analysis, we obtained four repeated measures in each woman in the four treatment arms. Analyses were done with SAS Version 9.4 software (SAS Institute, Inc, Cary, NC), using PROC MIXED (for mixed models). All models included the following four explanatory variables, regardless of whether they were statistically significant: 1) treatment group (TE, raloxifene, Rimostil, placebo); 2) week (W2, W4, W6, W8); 3) treatment group-by-week interaction; and 4) baseline value of the measure being analyzed. The inclusion of additional variables was evaluated individually for each outcome measure.

RESULTS

Sixty-six women were randomized into the trial, four women dropped out of the trial, and 62 women were included in the final data analysis. No effect of treatment group was observed in either the Center for Epidemiology Studies Depression Scale (P = 0.34) or Beck Depression Inventory (P = 0.27) scores; however, there was a difference in HRSD scores between treatment groups (P = 0.0037) that pair-wise comparisons of the combined weekly scores in each treatment demonstrated TE's beneficial effects on HRSD scores compared with Rimostil (P = 0.0005), and less consistently with placebo (P = 0.099). The average (SD) of the baseline scores for each treatment group on the HRSD was as follows: TE-15.3 (4.5), raloxifene-16.0 (3.7), Rimostil-14.0 (2.7), and placebo-15.2 (3.0). Whereas the HRSD scores after 8 weeks of treatment (least-square means) were TE-5.2(1.1), raloxifene-5.8(1.2), Rimostil-11.2(1.4), and placebo-7.8(1.1). No differences were observed between raloxifene and either TE or placebo in any scale score. HRSD scores in women assigned to TE were improved compared with those on Rimostil during weeks 6 and 8 (P values = 0.0008, 0.0011, respectively). Cognitive testing at week 8 showed that none of the three active treatment groups performed better than placebo.

CONCLUSIONS

This study did not identify significant therapeutic benefits of TE, Rimostil, or raloxifene compared with placebo in PMD. However, improvements in depression ratings were observed between TE compared with Rimostil. Thus, our findings do not support the role of ERbeta compounds in the treatment of PMD (and indeed could suggest a more important role of ERalpha).

Neuroimmunology of the female brain across the lifespan: Plasticity to psychopathology

The female brain is highly dynamic and can fundamentally remodel throughout the normal ovarian cycle as well as in critical life stages including perinatal development, pregnancy and old-age. As such, females are particularly vulnerable to infections, psychological disorders, certain cancers, and cognitive impairments. We will present the latest evidence on the female brain; how it develops through the neonatal period; how it changes through the ovarian cycle in normal individuals; how it adapts to pregnancy and postpartum; how it responds to illness and disease, particularly cancer; and, finally, how it is shaped by old age. Throughout, we will highlight female vulnerability to and resilience against disease and dysfunction in the face of environmental challenges.

Cancer and cancer survival modulates brain and behavior in a time-of-day-dependent manner in mice

Improvements in breast cancer therapy/diagnosis have substantially increased the cancer survivor population, although many survivors report persistent mental health issues including fatigue, mood and anxiety disorders, and cognitive impairments. These behavioral symptoms impair quality-of-life and are often associated with increased inflammation. Nocturnal rodent models of cancer are critical to the identification of the neurobiological mechanisms underlying these behavioral changes. Although both behavior and immunity display distinct diurnal patterns, most rodent research in this field is performed during the rodents’ inactive (light) period, which could potentially undermine the conclusions and clinical relevance. Therefore, here we tested the extent to which mammary tumors or tumor resection (“survivors”) in mice affects behavior and neuroinflammation in a nyctohemeral (day versus night)-dependent manner. Indeed, only the dark (active) phase unmasked fatigue-like behavior and altered novel object investigation for both tumor-bearing and -resected mice relative to surgical controls. Several inflammatory markers were expressed in a time-of-day-dependent manner (lower in the dark phase) in the blood and brains of surgical control mice, whereas this temporal pattern was absent (IL-1β, CXCL1, Myd88, Cd4) or reversed (C3) in the respective tissues of tumor-bearing and -resected mice. Taken together, these data indicate that the time of day of assessment significantly modulates various persistent and transient tumor-induced behavioral and immune changes.

Sex Differences in Antidepressant Effect of Sertraline in Transgenic Mouse Models

The main purpose of this study is to explore sex differences in the antidepressant effect of sertraline in genetic knockout or overexpression estrogen-synthesizing enzyme aromatase (Ar) gene mouse models in the forced swim test (FST). Our results demonstrated a significant reduction of depression-like behavior in the mice with overexpression of brain aromatase (Thy1-Ar) compared to sex- and age-matched Ar^+/− mice or wild type control mice. Using HPLC analysis, we also found an association between the brain estrogen-related antidepressive behavior and the regulation of serotonin (5-HT) system. Interestingly, a single dose administration of sertraline (10 mg/kg, i.p.) induced reduction of immobility time was found in all genotypes, except male Ar^+/− mice. While the underlying mechanisms of sex-specific response on antidepressive effect of sertraline remain to be investigated, our data showed that female mice appear to be more sensitive to sertraline-induced changes of 5-HT system than male mice in the prefrontal cortex (PFC) and the hippocampus (HPC). Further investigation of sex-specific effect of brain estrogen on antidepressant is needed.

Maternal Deprivation Increases Anxiety- and Depressive-Like Behaviors in an Age-Dependent Fashion and Reduces Neuropeptide Y Expression in the Amygdala and Hippocampus of Male and Female Young Adult Rats

Maternal deprivation for 24 h produces an immediate increase in basal and stress-induced corticosterone (CORT) secretion. Given the impact of elevated CORT levels on brain development, the goal of the present study was to characterize the effects of maternal deprivation at postnatal days 3 (DEP3) or 11 (DEP11) on emotional behavior and neuropeptide Y immunoreactivity (NPY-ir) in the basolateral amygdala (BLA) and dorsal hippocampus (dHPC) of male and female rats. Litters were distributed in control non-deprived (CTL), DEP3, or DEP11 groups. In Experiment 1, within each litter, one male and one female were submitted to one of the following tests: novelty suppressed feeding (NSF), sucrose negative contrast test (SNCT), and forced swimming test (FST), between postnatal days 52 and 60. In Experiment 2, two males and two females per litter were exposed to the elevated plus maze and 1 h later, perfused for investigation of NPY-ir, on PND 52. The results showed that DEP3 rats displayed greater anxiety-like behavior in the NSF and EPM, compared to CTL and DEP11 counterparts. In the SNCT, DEP3 and DEP11 males showed less suppression of the lower sucrose concentration intake, whereas all females suppressed less than males. Both manipulated groups displayed more immobility in the FST, although this effect was greater in DEP3 than in DEP11 rats. NPY-ir was reduced in DEP3 and DEP11 males and females in the BLA, whereas in the dHPC, DEP3 males showed less NPY-ir than DEP11, which, in turn, presented less NPY-ir than CTL rats. Females showed less NPY-ir than males in both structures. Because the deprivation effects were more intense in DEP3 than in DEP11, in Experiment 3, the frequency of nursing posture, licking-grooming, and interaction with pups was assessed upon litter reunion with mothers. Mothers of DEP11 litters engaged more in anogenital licking than mothers of DEP3 litters. The present results indicate that maternal deprivation changed affective behavior with greater impact in the earlier age and reduced the expression of NPY in emotion-related brain areas. The age-dependent differential effects of deprivation on maternal behavior could, at least in part, explain the outcomes in young adult rats.

The effect of estrogenic compounds on psychosis-like behaviour in female rats

17β-estradiol treatment has shown benefit against schizophrenia symptoms, however long-term use may be associated with negative side-effects. Selective estrogen receptor modulators, such as raloxifene and tamoxifen, have been proposed as suitable alternatives to 17β-estradiol. An isomer of 17β-estradiol, 17α-estradiol, is considered less carcinogenic, and non-feminising in males, however little is known about its potential as a treatment for schizophrenia. Moreover, the mechanism underlying the therapeutic action of estrogens remains unclear. We aimed to investigate the ability of these estrogenic compounds to attenuate psychosis-like behaviour in rats. We used two acute pharmacologically-induced assays of psychosis-like behaviour: psychotomimetic drug-induced hyperlocomotion and disruption of prepulse inhibition (PPI). Female Long Evans rats were either intact, ovariectomised (OVX), or OVX and chronically treated with 17β-estradiol, 17α-estradiol, raloxifene or tamoxifen. Only 17β-estradiol treatment attenuated locomotor hyperactivity induced by the indirect dopamine receptor agonist, methamphetamine. 17β-estradiol- and tamoxifen-treated rats showed attenuated methamphetamine- and apomorphine (dopamine D1/D2 receptor agonist)-induced disruption of PPI. Raloxifene-treated rats showed attenuated apomorphine-induced PPI disruption only. Baseline PPI was significantly reduced following OVX, and this deficit was reversed by all estrogenic compounds. Further, PPI in OVX rats was increased following administration of apomorphine. This study confirms a protective effect of 17β-estradiol in two established animal models of psychosis, while tamoxifen showed beneficial effects against PPI disruption. In contrast, 17α-estradiol and raloxifene showed little effect on dopamine receptor-mediated psychosis-like behaviours. This study highlights the utility of some estrogenic compounds to attenuate psychosis-like behaviour in rats, supporting the notion that estrogens have therapeutic potential for psychotic disorders.

The Phytoestrogen Genistein Produces Similar Effects as 17β-Estradiol on Anxiety-Like Behavior in Rats at 12 Weeks after Ovariectomy

The phytoestrogen genistein produces anxiolytic-like effects in ovariectomized rats, which highlights its potential therapeutic effect in ameliorating anxiety in surgical menopausal women. However, no studies have directly compared the effects of identical doses of genistein and 17β-estradiol, the main estrogen used in hormone replacement therapy in menopausal women. The present study evaluated the anxiolytic-like effects of identical doses of genistein and 17β-estradiol (0.045, 0.09, and 0.18 mg/kg/7 days, s.c.) in a surgical menopause model in rats in the elevated plus maze and locomotor activity tests at 12 weeks after ovariectomy. Additionally, the participation of estrogen receptor-β in the anxiolytic-like effect of genistein and 17β-estradiol was explored by previous administration of the 5 mg/kg tamoxifen antagonist. Genistein and 17β-estradiol (0.09 and 0.18 mg/kg) similarly reduced anxiety-like behavior in the elevated plus maze and also increased the time spent grooming and rearing, without affecting crossing in locomotor activity test. These effects were blocked by tamoxifen. Present results indicate that the phytoestrogen genistein has a similar behavioral profile as 17β-estradiol in rats at 12 weeks after ovariectomy through action at the estrogen receptor-β. Thus genistein has potential for reducing anxiety-like behavior associated with low concentrations of ovarian hormones, which normally occurs during natural and surgical menopause.

Novel oestrogen receptor β-selective ligand reduces obesity and depressive-like behaviour in ovariectomized mice

Hormonal changes due to menopause can cause various health problems including weight gain and depressive symptoms. Multiple lines of evidence indicate that oestrogen receptors (ERs) play a major role in postmenopausal obesity and depression. However, little is known regarding the ER subtype-specific effects on obesity and depressive symptoms. To delineate potential effects of ERβ activation in postmenopausal women, we investigated the effects of a novel oestrogen receptor β-selective ligand (C-1) in ovariectomized mice. Uterine weight, depressive behaviour, and weight gain were examined in sham-operated control mice and ovariectomized mice administered placebo, C-1, or 17β-oestradiol (E2). Administration of C-1 or E2 reduced body weight gain and depressive-like behaviour in ovariectomized mice, as assessed by the forced swim test. In addition, administration of E2 to ovariectomized mice increased uterine weight, but administration of C-1 did not result in a significant increase in uterine weight. These results suggest that the selective activation of ERβ in ovariectomized mice may have protective effects against obesity and depressive-like behaviour without causing an increase in uterine weight. The present findings raise the possibility of the application of ERβ-ligands such as C-1 as a novel treatment for obesity and depression in postmenopausal women.

Progesterone increased β-endorphin innervation of the locus coeruleus, but ovarian steroids had no effect on noradrenergic neurodegeneration

With the decline of ovarian steroids levels at menopause, many women experience an increase in anxiety and stress sensitivity. The locus coeruleus (LC), a central source of noradrenaline (NE), is activated by stress and is inhibited by β-endorphin. Moreover, increased NE has been implicated in pathological anxiety syndromes. Hormone replacement therapy (HRT) in menopause appears to decrease anxiety and vulnerability to stress. Therefore, we questioned the effect of HRT on the inhibitory β-endorphin innervation of the LC. In addition, we found that progesterone protects serotoninergic neurons in monkeys, leading us to question whether ovarian steroids are also neuroprotective in LC neurons in monkeys. Adult Rhesus monkeys (Macaca mulatta) were ovariectomized, and either treated with Silastic capsules that contained estradiol, estradiol+progesterone, progesterone alone or that were empty (ovariectomized; control). After 1month, the LC was obtained and processed for immunohistochemistry for β-endorphin and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL). The density of β-endorphin axons was determined with image analysis using ImageJ. The TUNEL-positive neurons were counted in the entire LC. Progesterone-alone significantly increased the density of the β-endorphin axons in the LC (p<0.01). No significant differences between groups in the number of TUNEL-positive cells in the LC were found. In conclusion, we found that HRT increases the inhibitory influence of β-endorphin in the LC, which could, in turn, contribute to reduce anxiety and increase stress resilience. In addition, we did not find compelling evidence of neurodegeneration or neuroprotection by HRT in the LC of Rhesus monkeys.

Comparing the effects of 17β-oestradiol and the selective oestrogen receptor modulators, raloxifene and tamoxifen, on prepulse inhibition in female rats

BACKGROUND

Evidence suggests that oestrogen plays a protective role against the development and severity of schizophrenia. However, while oestrogen may be beneficial as a treatment in schizophrenia, its chronic use is associated with side-effects. Selective oestrogen receptor modulators (SERMs) may provide an alternative, however little is known about the mechanism underlying their effects in schizophrenia.

METHODS

We investigated the effect of raloxifene and tamoxifen on dopaminergic-induced disruptions of prepulse inhibition (PPI). PPI measures sensorimotor gating and PPI disruptions are considered an endophenotype for schizophrenia. Adult female Sprague-Dawley rats were either intact, ovariectomized (OVX), OVX and 17β-oestradiol-treated, OVX and raloxifene-treated (low or high dose), or OVX and tamoxifen-treated (low or high dose).

RESULTS

The dopamine D1/D2 receptor agonist, apomorphine (0, 0.1, 0.3 and 1mg/kg), caused the expected dose-dependent disruption in PPI in intact and OVX rats. This PPI disruption was prevented in OVX rats treated with 17β-oestradiol, a high dose of raloxifene or a high dose of tamoxifen. In untreated OVX rats, average PPI was 55% after saline and 34% after 1mg/kg apomorphine treatment, a reduction of 21%. However, oestradiol-treated and raloxifene-treated OVX rats showed only a 7% PPI reduction, and tamoxifen-treated OVX rats had a 4% PPI reduction caused by apomorphine treatment. Startle amplitude was not different between the groups.

CONCLUSION

The SERMs, raloxifene and tamoxifen, can prevent dopamine D1/D2 receptor-mediated disruptions of sensorimotor gating, similar to oestradiol. These data lend support for the use of SERMs as a treatment for schizophrenia.

The Selective Estrogen Receptor Modulator Raloxifene Regulates Arginine-Vasopressin Gene Expression in Human Female Neuroblastoma Cells Through G Protein-Coupled Estrogen Receptor and ERK Signaling

The selective estrogen receptor modulator raloxifene reduces blood pressure in hypertensive postmenopausal women. In the present study we have explored whether raloxifene regulates gene expression of arginine vasopressin (AVP), which is involved in the pathogenesis of hypertension. The effect of raloxifene was assessed in human female SH-SY5Y neuroblastoma cells, which have been recently identified as a suitable cellular model to study the estrogenic regulation of AVP. Raloxifene, within a concentration ranging from 10(-10) M to 10(-6) M, decreased the mRNA levels of AVP in SH-SY5Y cells with maximal effect at 10(-7) M. This effect of raloxifene was imitated by an agonist (±)-1-[(3aR*,4S*,9bS*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone of G protein-coupled estrogen receptor-1 (GPER) and blocked by an antagonist (3aS*,4R*,9bR*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-3H-cyclopenta[c]quinoline of GPER and by GPER silencing. Raloxifene induced a time-dependent increase in the level of phosphorylated ERK1 and ERK2, by a mechanism blocked by the GPER antagonist. The treatment of SH-SY5Y cells with either a MAPK/ERK kinase 1/2-specific inhibitor (1,4-diamino-2, 3-dicyano-1,4-bis(2-aminophenylthio)butadine) or a protein kinase C inhibitor (sotrastaurin) blocked the effects of raloxifene on the phosphorylation of ERK1/2 and the regulation of AVP mRNA levels. These results reveal a mechanism mediating the regulation of AVP expression by raloxifene, involving the activation of GPER, which in turn activates protein kinase C, MAPK/ERK kinase, and ERK. The regulation of AVP by raloxifene and GPER may have implications for the treatment of blood hypertension(.).

Pre-treatment effects of peripheral tumors on brain and behavior: neuroinflammatory mechanisms in humans and rodents

Cancer patients suffer high levels of affective and cognitive disturbances, which have been attributed to diagnosis-related distress, impairment of quality of life, and side effects of primary treatment. An inflammatory microenvironment is also a feature of the vast majority of solid tumors. However, the ability of tumor-associated biological processes to affect the central nervous system (CNS) has only recently been explored in the context of symptoms of depression and cognitive disturbances. In this review, we summarize the burgeoning evidence from rodent cancer models that solid tumors alter neurobiological pathways and subsequent behavioral processes with relevance to affective and cognitive disturbances reported in human cancer populations. We consider, in parallel, the evidence from human clinical cancer research demonstrating that affective and cognitive disturbances are common in some malignancies prior to diagnosis and treatment. We further consider the underlying neurobiological pathways, including altered neuroinflammation, tryptophan metabolism, prostaglandin synthesis and associated neuroanatomical changes, that are most strongly implicated in the rodent literature and supported by analogous evidence from human cancer populations. We focus on the implications of these findings for behavioral researchers and clinicians, with particular emphasis on methodological issues and areas of future research.

Tamoxifen antagonizes the effects of ovarian hormones to induce anxiety and depression-like behavior in rats

The effects of tamoxifen (TAM) on anxiety and depression-like behavior in ovariectomized (OVX) and naïve female rats were investigated. The animals were divided into Sham-TAM, OVX-TAM, Sham and OVX groups. Tamoxifen (1 mg/kg) was administered for 4 weeks. In the forced swimming test, the immobility times in the OVX and Sham-TAM groups were higher than in the Sham group. In the open field, the numbers of central crossings in the OVX and Sham-TAM groups were lower than the number in the Sham group, and the number of peripheral crossings in the OVX group was lower than the number in the Sham group. In the elevated plus maze, the numbers of entries to the open arm among the animals in the Sham-TAM and OVX groups were lower than the number in the Sham group, while the number of entries to the open arm in the OVX-TAM group was higher than the number in the OVX group. It was shown that deletion of ovarian hormones induced anxiety and depression-like behavior. Administration of tamoxifen in naïve rats led to anxiety and depression-like behavior that was comparable with the effects of ovarian hormone deletion. It can be suggested that tamoxifen antagonizes the effects of ovarian hormones. It also seems that tamoxifen has anxiolytic effects on ovariectomized rats.

The neuroprotective actions of oestradiol and oestrogen receptors

Hormones regulate homeostasis by communicating through the bloodstream to the body's organs, including the brain. As homeostatic regulators of brain function, some hormones exert neuroprotective actions. This is the case for the ovarian hormone 17β-oestradiol, which signals through oestrogen receptors (ERs) that are widely distributed in the male and female brain. Recent discoveries have shown that oestradiol is not only a reproductive hormone but also a brain-derived neuroprotective factor in males and females and that ERs coordinate multiple signalling mechanisms that protect the brain from neurodegenerative diseases, affective disorders and cognitive decline.

Republished study: long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize

BACKGROUND

The health effects of a Roundup-tolerant NK603 genetically modified (GM) maize (from 11% in the diet), cultivated with or without Roundup application and Roundup alone (from 0.1 ppb of the full pesticide containing glyphosate and adjuvants) in drinking water, were evaluated for 2 years in rats. This study constitutes a follow-up investigation of a 90-day feeding study conducted by Monsanto in order to obtain commercial release of this GMO, employing the same rat strain and analyzing biochemical parameters on the same number of animals per group as our investigation. Our research represents the first chronic study on these substances, in which all observations including tumors are reported chronologically. Thus, it was not designed as a carcinogenicity study. We report the major findings with 34 organs observed and 56 parameters analyzed at 11 time points for most organs.

RESULTS

Biochemical analyses confirmed very significant chronic kidney deficiencies, for all treatments and both sexes; 76% of the altered parameters were kidney-related. In treated males, liver congestions and necrosis were 2.5 to 5.5 times higher. Marked and severe nephropathies were also generally 1.3 to 2.3 times greater. In females, all treatment groups showed a two- to threefold increase in mortality, and deaths were earlier. This difference was also evident in three male groups fed with GM maize. All results were hormone- and sex-dependent, and the pathological profiles were comparable. Females developed large mammary tumors more frequently and before controls; the pituitary was the second most disabled organ; the sex hormonal balance was modified by consumption of GM maize and Roundup treatments. Males presented up to four times more large palpable tumors starting 600 days earlier than in the control group, in which only one tumor was noted. These results may be explained by not only the non-linear endocrine-disrupting effects of Roundup but also by the overexpression of the EPSPS transgene or other mutational effects in the GM maize and their metabolic consequences.

CONCLUSION

Our findings imply that long-term (2 year) feeding trials need to be conducted to thoroughly evaluate the safety of GM foods and pesticides in their full commercial formulations.

Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize

The health effects of a Roundup-tolerant genetically modified maize (from 11% in the diet), cultivated with or without Roundup, and Roundup alone (from 0.1 ppb in water), were studied 2 years in rats. In females, all treated groups died 2-3 times more than controls, and more rapidly. This difference was visible in 3 male groups fed GMOs. All results were hormone and sex dependent, and the pathological profiles were comparable. Females developed large mammary tumors almost always more often than and before controls, the pituitary was the second most disabled organ; the sex hormonal balance was modified by GMO and Roundup treatments. In treated males, liver congestions and necrosis were 2.5-5.5 times higher. This pathology was confirmed by optic and transmission electron microscopy. Marked and severe kidney nephropathies were also generally 1.3-2.3 greater. Males presented 4 times more large palpable tumors than controls which occurred up to 600 days earlier. Biochemistry data confirmed very significant kidney chronic deficiencies; for all treatments and both sexes, 76% of the altered parameters were kidney related. These results can be explained by the non linear endocrine-disrupting effects of Roundup, but also by the overexpression of the transgene in the GMO and its metabolic consequences.

Activation of amygdalar metabotropic glutamate receptors modulates anxiety, and risk assessment behaviors in ovariectomized estradiol-treated female rats

Anxiety disorders are more prevalent in females than males. The underlying reasons for this gender difference are unknown. Metabotropic glutamate receptors (mGluRs) have been linked to anxiety and it has been shown that interaction between estrogen receptors and mGluRs modulate sexual receptivity in rats. We investigated the role of mGluRs in anxiety-related behaviors in ovariectomized female rats with (OVX+EB) or without (OVX) estradiol implants. We centrally infused (s)-3,5-dihydroxyphenylglycine (DHPG), a group I mGluR agonist, into the basolateral amygdala (BLA) of OVX+EB and OVX rats at 0.1 and 1.0 μM. Male rats that normally have low estradiol levels were used to compare with OVX rats. Generalized anxiety, explorative activity and detection and analysis of threat were analyzed in the elevated plus maze (EPM) and risk assessment behaviors (RABs). DHPG (1.0 μM) increased the percentage of time spent in- and entries into- the open arms in OVX+EB, but not in OVX or male rats. Flat-back approaches and stretch-attend postures, two RABs, were significantly reduced by DHPG (0.1 and 1.0 μM) in OVX+EB rats only. DHPG did not modulate rearing and freezing, behaviors related to exploration and fear-like behavior, respectively. However, DHPG (1.0 μM) increased head dipping and decreased grooming behaviors in OVX rats, suggesting a weak explorative modulation. The effects of DHPG observed in OVX+EB, were blocked by 50 μM of (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA), a mGluR1 antagonist. AIDA and/or estradiol did not modulate anxiety and or RABs. Our results show that intra-BLA infusion of DHPG exerts an anxiolytic-like effect in OVX+EB, but not in OVX or male rats. This effect seems to depend upon mGluR1 subtype activation. Our findings led us to suggest that the effects observed in OVX+EB rats might be due to an interaction at the membrane level of estrogen receptors with mGlu1 within the BLA.

Neuroprotective actions of estradiol revisited

Results from animal experiments showing that estradiol is neuroprotective were challenged 10 years ago by findings indicating an increased risk of dementia and stroke in women over 65 years of age taking conjugated equine estrogens. Our understanding of the complex signaling of estradiol in neural cells has recently clarified the causes of this discrepancy. New data indicate that estradiol may lose its neuroprotective activity or even increase neural damage, a situation that depends on the duration of ovarian hormone deprivation and on age-associated modifications in the levels of other molecules that modulate estradiol action. These studies highlight the complex neuroprotective mechanisms of estradiol and suggest a window of opportunity during which effective hormonal therapy could promote brain function and cognition.

Antidepressive and anxiolytic activity of selective estrogen receptor modulators in ovariectomized mice submitted to chronic unpredictable stress

Estradiol has antidepressive and anxiolytic actions. However, its therapeutic use is limited by its peripheral effects. Selective estrogen receptor modulators may represent an alternative to estradiol for the treatment of depressive symptoms. Here we report that tamoxifen and raloxifene decrease immobility time in the forced swim test and increases the time spent in open arms in the elevated plus maze in ovariectomized mice submitted to chronic unpredictable stress.

Hormones, heart disease, and health: individualized medicine versus throwing the baby out with the bathwater

It is increasingly axiomatic that depression has widespread adverse physiological effects and, conversely, that a variety of physiological systems impact the risk for developing depression. This convergence of depression and altered physiology is particularly dramatic during midlife--a time during which reproductive failure presages dramatic increases in prevalence of both heart disease and depression. The potentially meaningful and illuminating links between estrogen deficiency, cardiovascular disease (CVD), and depression have largely been obscured, first by assertions, subsequently repudiated, that the perimenopause was not a time of increased risk of depression, and more recently by the denegration of hormone replacement therapy by initial reports of the Women's Health Initiative. Increasingly, however, research has led to unavoidable conclusions that CVD and depression share common, mediating pathogenic processes and that these same processes are dramatically altered by the presence or absence of estrogen (E2). This review summarizes data supporting these contentions with the intent of placing depression and estrogen therapy in their proper physiologic context.

Hormones, heart disease, and health: individualized medicine versus throwing the baby out with the bathwater

It is increasingly axiomatic that depression has widespread adverse physiological effects, and conversely that a variety of physiological systems impact the risk for developing depression. This convergence of depression and altered physiology is particularly dramatic during midlife-a time during which reproductive failure presages dramatic increases in prevalence of both heart disease and depression. The potentially meaningful and illuminating links between estrogen (E2) deficiency, cardiovascular disease (CVD), and depression have largely been obscured, first by assertions, subsequently repudiated that the perimenopause was not a time of increased risk of depression, and more recently by the denegration of hormone replacement therapy by initial reports of the Women's Health Initiative. Increasingly, however, research has led to unavoidable conclusions that CVD and depression share common and mediating pathogenic processes and that these same processes are dramatically altered by the presence or absence of E2. This review summarizes data supporting this contention with the intent of placing depression and E2 therapy in their proper physiologic context.

Anti-anxiety, cognitive, and steroid biosynthetic effects of an isoflavone-based dietary supplement are gonad and sex-dependent in rats

Isoflavone-rich diets are associated with reduced menopausal symptoms and lowered risk of cancers of reproductive tissues. Isoflavones may mimic some effects of estrogen by binding to estrogen receptors, and/or altering steroid availability. Despite their potential health benefits, neither the effects, nor mechanisms, of isoflavones are well understood. We hypothesized that isoflavones would alter behavior and physiology of rats in sex and/or gonad-dependent manner. An isoflavone-based, commercially-available, dietary supplement was administered via subcutaneous implantation to female and male, intact and gonadectomized Long-Evans rats. Affective (elevated plus-maze), cognitive (water-maze), and reproductive (sexual) behavior was examined. Weights of reproductive structures were measured, as an index of trophic effects. Steroid levels in circulation and brain regions associated with behavioral measures were evaluated by radioimmunoassay. The supplement increased anti-anxiety behavior of intact, but not gonadectomized, rats. The supplement enhanced visual-spatial performance of all rats, but this effect was most evident among proestrous female rats, which had the poorest spatial performance. There were neither effects of the supplement on sexual behavior, mass of reproductive tissues, nor plasma steroid levels. The supplement increased levels of 5α-androstane,17ß-diol-3α-diol (3α-diol) in the hippocampus (but not other brain regions) of gonadectomized females. Thus, the supplement altered anxiety and cognitive behavior and brain production of steroids; however, the anti-anxiety effects were limited to rats with an intact reproductive axis and effects on cognitive performance and neurosteriodogenesis were most evident among intact and gonadectomized, female rats respectively.

Antidepressant effects of estrogens: a basic approximation

The use of estrogenic compounds as antidepressants or as coadjuvants to facilitate the effect of antidepressants has reported controversial results, suggesting that many factors could influence their actions. This review analyzes, from a basic research perspective, the possible factors that may underlie the antidepressant action of estrogens alone or in combination. The possible mechanisms of action of estrogens alone and in combination with the selective serotonin reuptake inhibitor, fluoxetine, the selective noradrenaline reuptake inhibitor, desipramine, and the mixed serotonin/noradrenaline reuptake inhibitor, venlafaxine are reviewed, focusing on monoaminergic systems and estrogen receptors as main targets. The antidepressant effect of estrogens depends on the type of estrogen, treatment duration, doses, sex, time after ovariectomy, and age. Estrogens potentiate the antidepressant-like action of fluoxetine, venlafaxine, and desipramine and drastically shorten their latency of action. The antidepressant-like effect of estrogens alone or in combination with antidepressants seems to be mediated by monoaminergic and classic estrogen receptors, as WAY100635, an antagonist to the serotonin 1A receptor, idaxozan, an antagonist to alpha2 adrenergic receptors, and RU 58668, an estrogen receptor antagonist, blocked their antidepressant-like effect. In conclusion, estrogens produce antidepressant-like actions by themselves and importantly facilitate the action of clinically used antidepressants.

Conjugated equine estrogen, with medroxyprogesterone acetate, enhances formation of 5alpha-reduced progestogens and reduces anxiety-like behavior of middle-aged rats

The mechanisms by which progestogens influence affective behaviors in females are poorly understood despite clear changes in mood/affect that are associated with their decline during menopause. Conjugated equine estrogens (CEE), with or without medroxyprogesterone acetate (MPA), are commonly prescribed hormone-replacement, but there is heterogeneity in responses to these pharmacotherapies. One way in which these compounds differ is in their capacity to potentiate metabolism of progesterone to its 5alpha-reduced products, dihydroprogesterone and 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP). This study investigated whether responses to CEE and MPA may be related to the capacity to metabolize progesterone. Middle-aged female rats that had maintained reproductive status, or those that had a decline, were administered vehicle, CEE and/or MPA. Effects on anxiety-like (open field, elevated plus maze) and social behaviors (social interaction test), and plasma and hippocampus steroid levels were determined. We hypothesized that CEE, but not MPA, would decrease anxiety-like behavior coincident with increased hippocampal metabolism of progesterone. CEE, or CEE+MPA, increased central entries in the open field and time spent on the open arms of the plus maze, but did not alter social interaction of rats that had maintained reproductive status. CEE and/or CEE+MPA increased E2 and 3alpha,5alpha-THP in plasma and/or hippocampus of rats, but MPA increased levels of dihydroprogesterone in the hippocampus of rats with declining reproductive status. Simple regressions showed that hippocampus 3alpha,5alpha-THP levels accounted for a significant proportion of the variance in anxiety-like behavior. Therefore, effects of CEE to reduce anxiety-like behavior of middle-aged rats may be owing, in part, to its capacity to enhance levels of 3alpha,5alpha-THP in the hippocampus.