Estradiol inhibits GSK3 and regulates interaction of estrogen receptors, GSK3, and beta-catenin in the hippocampus

Health risks of Bisphenol-A exposure: From Wnt signaling perspective

Human beings are routinely exposed to chronic and low dose of Bisphenols (BPs) due to their widely pervasiveness in the environment. BPs hold similar chemical structures to 17β-estradiol (E2) and thyroid hormone, thus posing threats to human health by rendering the endocrine system dysfunctional. Among BPs, Bisphenol-A (BPA) is the best-known and extensively studied endocrine disrupting compound (EDC). BPA possesses multisystem toxicity, including reproductive toxicity, neurotoxicity, hepatoxicity and nephrotoxicity. Particularly, the central nervous system (CNS), especially the developing one, is vulnerable to BPA exposure. This review describes our current knowledge of BPA toxicity and the related molecular mechanisms, with an emphasis on the role of Wnt signaling in the related processes. We also discuss the role of oxidative stress, endocrine signaling and epigenetics in the regulation of Wnt signaling by BPA exposure. In summary, dysfunction of Wnt signaling plays a key role in BPA toxicity and thus can be a potential target to alleviate EDCs induced damage to organisms.

Sex-associated microRNAs potentially implicated in sporadic Alzheimer's disease (sAD)

BACKGROUND

The onset and pathology of sporadic Alzheimer's disease (sAD) seem to be affected by both sex and genetic mechanisms. Evidence supports that the high prevalence of sAD in women, worldwide, may be attributed to an interplay among aging, sex, and lifestyle, influenced by genetics, metabolic changes, and hormones. Interestingly, epigenetic mechanisms such as microRNAs (miRNAs), known as master regulators of gene expression, may contribute to this observed sexual dimorphism in sAD.

OBJECTIVES

To investigate the potential impact of sex-associated miRNAs on processes manifesting sAD pathology, as described by the Tau-driven Adverse Outcome Pathway (AOP) leading to memory loss.

METHODS

Using publicly available human miRNA datasets, sex-biased miRNAs, defined as differentially expressed by sex in tissues possibly affected by sAD pathology, were collected. In addition, sex hormone-related miRNAs were also retrieved from the literature. The compiled sex-biased and sex hormone-related miRNAs were further plugged into the dysregulated processes of the Tau-driven AOP for memory loss.

RESULTS

Several miRNAs, previously identified as sex-associated, were implicated in dysregulated processes associated with the manifestation of sAD pathology. Importantly, the described pathology processes were not confined to a particular sex. A mechanistic-based approach utilizing miRNAs was adopted in order to elucidate the link between sex and biological processes potentially involved in the development of memory loss.

CONCLUSIONS

The identification of sex-associated miRNAs involved in the early processes manifesting memory loss may shed light to the complex molecular mechanisms underlying sAD pathogenesis in a sex-specific manner.

Estradiol enhanced neuronal plasticity and ameliorated astrogliosis in human iPSC-derived neural models

Introduction

17β-Estradiol (E2) is a sex hormone that has been previously demonstrated to have neurotherapeutic effects on animal models of Alzheimer's disease (AD). However, clinical trials on E2 replacement therapy for preventing AD onset yielded inconsistent results. Therefore, it is imperative to clarify the therapeutic effects of E2 on human cells. In this study, we utilized induced pluripotent stem cells (iPSCs) derived from multiple AD donors to explore the therapeutic effects of E2 on the in vitro model of human cells.

Methods

We conducted a systematic review and meta-analysis using a random-effects model of the previously reported AD clinical trials to summarize the effects of E2 replacement therapy on AD prevention. Subsequently, we induced iPSCs from the donors of the healthy control (1210B2 line (female) and 201B7 line (female)), the familial AD (APP V717L line (female) and APP KM670/671NL line (female)), and the sporadic AD (UCSD-SAD3.7 line (APOE ε3/ε3) (male), UCSD-SAD7D line (APOE ε3/ε4) (male), and TMGH-1 line (APOE ε3/ε3) (female)), then differentiated to neurons. In addition to the mono-culture model of the neurons, we also examined the effects of E2 on the co-culture model of neurons and astrocytes.

Results

The meta-analysis of the clinical trials concluded that E2 replacement therapy reduced the risk of AD onset (OR, 0.69; 95 % confidence interval [CI], 0.53-0.91; I2 = 82 %). Neural models from the iPSCs of AD donors showed an increase in secreted amyloid-beta (Aβ) levels in the mono-culture model and an astrogliosis-like phenotype in the co-culture model. E2 treatment to the neuronal models derived from the iPSCs enhanced neuronal activity and increased neurite complexity. Furthermore, E2 treatment of the co-culture model ameliorated the astrogliosis-like phenotype. However, in contrast to the previous reports using mouse models, E2 treatment did not change AD pathogenesis, including Aβ secretion and phosphorylated tau (pTau) accumulation.

Conclusion

E2 treatment of the human cellular model did not impact Aβ secretion and pTau accumulation, but promoted neuronal plasticity and alleviated the astrogliosis-like phenotype. The limited effects of E2 may give a clue for the mixed results of E2 clinical trials.

Sex steroid and cognitive function among community-dwelling older men with or without vascular risk factors: a cross-sectional study

BACKGROUND

The relationship of testosterone and estradiol concentrations with cognitive function among community-dwelling older men was inconclusive. To examine the association of serum testosterone and estradiol concentrations with cognitive function in older men with or without vascular risk factors (VRFs).

METHODS

This cross-sectional study consisted of 224 community-dwelling men aged 65-90 years in the Songjiang District of Shanghai, China. Serum testosterone and estradiol were measured by electrochemiluminescence immunoassay. The following five factors were defined as VRFs in this study: obesity, history of hypertension, diabetes, stroke, and coronary heart disease. Multivariable linear regression was used to examine the association of testosterone and estradiol with the Mini-Mental State Examination (MMSE) in participants with or without VRF. Restricted cubic spline (RCS) regression was performed to account for the nonlinearity of these associations.

RESULTS

An inverted "U" shaped non-linear relationship was found between testosterone concentration and MMSE score in men with one VRF (P overall =.003, non-linear P =.002). Estradiol showed an inverted "U" shaped non-linear relationship with MMSE score independent of VRFs (men without VRF, P overall =.049, non-linear P =.015; men with one VRF, overall P =.007, non-linear P =.003; men with two or more VRFs, overall P =.009, non-linear P =.005).

CONCLUSION

In older men, an optimal level of sex steroid concentration may be beneficial to cognitive function and the VRFs should be considered when interpreting the relationship between sex steroid and cognitive function.

Overview of metabolomic aspects in postpartum depression

Along with the typical biochemical alterations that occur during pregnancy, certain metabolic changes might be associated with the development of several psychiatric disorders, including postpartum depression (PPD), which is the most common type of psychiatric disorder during pregnancy or first postpartum year, and it develops in about 15% of women. Metabolomics is a rapidly developing discipline that deals with the metabolites as the final products of all genetically controlled biochemical pathways, highly influenced by external and internal changes. The aim of this paper was to review the published studies whose results suggest or deny a possible association between the fine regulation of the metabolome and PPD, enabling conclusions about whether metabolomics could be a useful tool in defining the biochemical pathways directly involved in the etiology, diagnosis and course of PPD. Beside numerous hormonal changes, a lot of different metabolic pathways have been discovered to be affected in women with PPD or associated with its development, including alterations in the energy metabolism, tryptophan and amino acid metabolism, steroid metabolism, purine cycle, as well as neurotransmitter metabolism. Additionally, metabolomics helped in defining the association between PPD and the exposure to various endocrine disrupting metabolites during pregnancy. Finally, metabolome reflects different PPD therapies and exposure of fetus or breastfed infants to pharmacotherapy prescribed to a mother suffering from PPD. This review can help in creating the picture about metabolomics' broad application in PPD studies, but it also implies that its potential is still not completely used.

Effects of Artemisia annua L. on postmenopausal syndrome in ovariectomized mice

ETHNOPHARMACOLOGICAL RELEVANCE

Artemisia annua L. (Asteraceae) has been used as an antipyretic and anti-parasitic drug in traditional medicine for more than 2000 years. It has also been prescribed to treat symptoms caused by deficiency of Yin, which might be observed in menopausal state from the point of view of traditional medicine.

AIM OF THE STUDY

We hypothesized that A. annua might be useful for treating menopausal disorders with less adverse effects than hormone replacement therapy. Thus, the aim of the present study was to investigate effects of A. annua on postmenopausal symptoms of ovariectomized (OVX) mice.

MATERIALS AND METHODS

OVX mice were employed as a model for postmenopausal disorders. Mice were treated with a water extract of A. annua (EAA; 30, 100 or 300 mg/kg, p.o.) or 17β-estradiol (E2; 0.5 mg/kg, s.c.) for 8 weeks. Open field test (OFT), novel object recognition task (NOR), Y-maze test, elevated plus maze test (EPM), splash test and tail suspension test (TST) were conducted to determine whether EAA could ameliorate postmenopausal symptoms. Phosphorylated levels of extracellular signal-regulated kinase (ERK), protein kinase B (Akt), and glycogen synthase kinase-3β (GSK-3β), β-catenin and expression level of synaptophysin in the cortex and hippocampus were evaluated by Western blot analysis.

RESULTS

EAA treatment significantly increased the discrimination index in NOR, decreased the time in closed arm than in open arm in EPM, increased grooming time in splash test, and decreased immobility time in TST, as did E2 treatment. In addition, decreased phosphorylation levels of ERK, Akt, GSK-3β, and β-catenin and expression levels of synaptophysin in the cortex and hippocampus after OVX were reversed by administration of EAA and E2.

CONCLUSION

These results suggest that A. annua can ameliorate postmenopausal symptoms such as cognitive dysfunction, anxiety, anhedonia, and depression by activating ERK, Akt, and GSK-3β/β-catenin signaling pathway and hippocampal synaptic plasticity, and that A. annua would be a novel treatment for postmenopausal symptoms.

The Pathological Effects of Circulating Hydrophobic Bile Acids in Alzheimer's Disease

Recent clinical studies have revealed that the serum levels of toxic hydrophobic bile acids (deoxy cholic acid, lithocholic acid [LCA], and glycoursodeoxycholic acid) are significantly higher in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) when compared to control subjects. The elevated serum bile acids may be the result of hepatic peroxisomal dysfunction. Circulating hydrophobic bile acids are able to disrupt the blood-brain barrier and promote the formation of amyloid-β plaques through enhancing the oxidation of docosahexaenoic acid. Hydrophobic bile acid may find their ways into the neurons via the apical sodium-dependent bile acid transporter. It has been shown that hydrophobic bile acids impose their pathological effects by activating farnesoid X receptor and suppressing bile acid synthesis in the brain, blocking NMDA receptors, lowering brain oxysterol levels, and interfering with 17β-estradiol actions such as LCA by binding to E2 receptors (molecular modelling data exclusive to this paper). Hydrophobic bile acids may interfere with the sonic hedgehog signaling through alteration of cell membrane rafts and reducing brain 24(S)-hydroxycholesterol. This article will 1) analyze the pathological roles of circulating hydrophobic bile acids in the brain, 2) propose therapeutic approaches, and 3) conclude that consideration be given to reducing/monitoring toxic bile acid levels in patients with AD or aMCI, prior/in combination with other treatments.

Astragalin alleviates cognitive deficits and neuronal damage in SAMP8 mice through upregulating estrogen receptor expression

Senile plaques composed of β-amyloid protein (Aβ) and neurofibrillary tangles (NFTs) composed of intracellular hyper-phosphorylated tau are major causes of cognitive impairment and neuronal damage in Alzheimer disease (AD). Astragalin (AST), a naturally-occurring flavonoid compound, was reported to have neuroprotective effects in the brain, but its effects in AD remain unknown. Herein, the learning and memory deficits were alleviated and neuronal damage in the hippocampus were inhibited after the senescence-accelerated mouse prone 8 (SAMP8) mouse were given AST (5 mg/kg or 10 mg/kg) daily by gavage for 2 months. Furthermore, AST reduced Aβ_1-40 and Aβ_1-42 deposition, decreased β-carboxyl-terminal fragment (β-CTF) protein level and tau hyper-phosphorylation, but increased α-CTF protein level and glycogen synthase kinase-3beta (GSK-3β) phosphorylation in hippocampus of SAMP8 mice. Meanwhile, the effects of AST on AD were also explored in vitro by treating primary neurons with amyloid-β1-42 oligomers (Aβ_1-42O). Consistently, AST also alleviated amyloid-β1-42 oligomers (Aβ_1-42O)-induced neuronal damage, amyloid plaques, and tau phosphorylation in vitro model. Of note, estrogen receptor (ER)α and ERβ expression in the hippocampus of SAMP8 mice and Aβ_1-42O-treated neurons was significantly decreased but their levels were increased by AST. Moreover, in vivo and in vitro experiments revealed that ER antagonist, Fulvestrant, reversed the effects caused by AST. Altogether, our investigation indicates that AST may ameliorate cognitive deficits and AD-type pathologies in SAMP8 mice and Aβ_1-42O-treated neurons through upregulating ERα and ERβ expression. Our findings indicate the value of AST as a potential reagent for AD treatment.

Arsenic Induces GSK3β-dependent p-tau, neuronal apoptosis and cognitive impairment via an interdependent hippocampal ERα and IL-1/IL-1R1 mechanism in female rats

Arsenic is an environmental contaminant with potential neurotoxicity. We previously reported that arsenic promoted hippocampal neuronal apoptosis, inducing cognitive loss. Here, we correlated it with tau pathology. We observed that environmentally relevant arsenic exposure increased tau phosphorylation and the principal tau kinase, glycogen synthase kinase-3 beta (GSK3β), in the female rat hippocampal neurons. We detected the same in primary hippocampal neurons. Since a regulated estrogen receptor (ER) level and inflammation contributed to normal hippocampal functions, we examined their levels following arsenic exposure. Our ER screening data revealed that arsenic down-regulated hippocampal neuronal ERα. We also detected an up-regulated hippocampal interleukin-1 (IL-1) and its receptor, IL-1R1. Further, co-treating arsenic with the ERα agonist, 4,4',4''-(4-Propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT), or IL-1R antagonist (IL-1Ra) resulted in reduced GSK3β and p-tau, indicating involvement of decreased ERα and increased IL-1/IL-1R1 in tau hyperphosphorylation. We then checked whether ERα and IL-1/IL-1R1 had linkage, and detected that while PPT reduced IL-1 and IL-1R1, the IL-1Ra restored ERα, suggesting their arsenic-induced interdependence. We finally correlated this pathway with apoptosis and cognition. We observed that PPT, IL-1Ra and the GSK3β inhibitor, LiCl, reduced hippocampal neuronal cleaved caspase-3 and TUNEL+ve apoptotic count, and decreased the number of errors during learning and increased the saving-memory for Y-Maze Test and retention performance for Passive avoidance test in arsenic-treated rats. Thus, our study reveals a novel mechanism of arsenic-induced GSK3β-dependent tau pathology via interdependent ERα and IL-1/IL-1R1 signaling. It also envisages the protective role of ERα agonist and IL-1 inhibitor against arsenic-induced neurotoxicity.

Androgens Regulate Tau Phosphorylation Through Phosphatidylinositol 3-Kinase-Protein Kinase B-Glycogen Synthase Kinase 3β Signaling

Age-related testosterone depletion in men is a risk factor for Alzheimer's disease (AD). How testosterone modulates AD risk remains to be fully elucidated, although regulation of tau phosphorylation has been suggested as a contributing protective action. To investigate the relationship between testosterone and tau phosphorylation, we first evaluated the effect of androgen status on tau phosphorylation in 3xTg-AD mice. Depletion of endogenous androgens via gonadectomy resulted in increased tau phosphorylation that was prevented by acute testosterone treatment. Parallel alterations in the phosphorylation of both glycogen synthase kinase 3β (GSK3β) and protein kinase B (Akt) suggest possible components of the underlying signaling pathway. To further explore mechanism, primary cultured neurons were treated with a physiological concentration of testosterone or its active metabolite dihydrotestosterone (DHT). Results showed that testosterone and DHT induced significant decreases in phosphorylated tau and significant increases in phosphorylation of Akt and GSK3β. Pharmacological inhibition of phosphatidylinositol 3-kinase (PI3K) effectively inhibited androgen-induced increases in Akt and GSK3β phosphorylation, and decreases in tau phosphorylation. In addition, androgen receptor (AR) knock-down by small interfering RNA prevented androgen-induced changes in the phosphorylation of Akt, GSK3β and tau, suggesting an AR-dependent mechanism. Additional experiments demonstrated androgen-induced changes in Akt, GSK3β and tau phosphorylation in AR-expressing PC12 cells but not in AR-negative PC12 cells. Together, these results suggest an AR-dependent pathway involving PI3K-Akt-GSK3β signaling through which androgens can reduce tau phosphorylation. These findings identify an additional protective mechanism of androgens that can improve neural health and inhibit development of AD.

Comorbidity of osteoporosis and Alzheimer's disease: Is `AKT `-ing on cellular glucose uptake the missing link?

Osteoporosis and Alzheimer's disease (AD) are both degenerative diseases. Osteoporosis often proceeds cognitive deficits, and multiple studies have revealed common triggers that lead to energy deficits in brain and bone. Risk factors for osteoporosis and AD, such as obesity, type 2 diabetes, aging, chemotherapy, vitamin deficiency, alcohol abuse, and apolipoprotein Eε4 and/or Il-6 gene variants, reduce cellular glucose uptake, and protective factors, such as estrogen, insulin, exercise, mammalian target of rapamycin inhibitors, hydrogen sulfide, and most phytochemicals, increase uptake. Glucose uptake is a fine-tuned process that depends on an abundance of glucose transporters (Gluts) on the cell surface. Gluts are stored in vesicles under the plasma membrane, and protective factors cause these vesicles to fuse with the membrane, resulting in presentation of Gluts on the cell surface. This translocation depends mainly on AKT kinase signaling and can be affected by a range of factors. Reduced AKT kinase signaling results in intracellular glucose deprivation, which causes endoplasmic reticulum stress and iron depletion, leading to activation of HIF-1α, the transcription factor necessary for higher Glut expression. The link between diseases and aging is a topic of growing interest. Here, we show that diseases that affect the same biochemical pathways tend to co-occur, which may explain why osteoporosis and/or diabetes are often associated with AD.

Sex Differences and Estradiol Effects in MAPK and Akt Cell Signaling across Subregions of the Hippocampus

INTRODUCTION

Rapid effects of estrogens within the hippocampus of rodents are dependent upon cell-signaling cascades, and activation of these cascades by estrogens varies by sex. Whether these pathways are rapidly activated within the dentate gyrus (DG) and CA1 by estrogens across sex and the anatomical longitudinal axis has been overlooked.

METHODS

Gonadally intact female and male rats were given either vehicle or physiological systemic low (1.1 µg/kg) or high (37.3 µg/kg) doses of 17β-estradiol 30 min prior to tissue collection. To control for the effects of circulating estrogens, an additional group of female rats was ovariectomized (OVX) and administered 17β-estradiol. Brains were extracted, and tissue punches of the CA1 and DG were taken along the longitudinal hippocampal axis (dorsal and ventral) and analyzed for key mitogen-activated protein kinase (MAPK) and protein kinase B (Akt) cascade phosphoproteins.

RESULTS

Intact females had higher Akt pathway phosphoproteins (pAkt, pGSK-3β, and pp70S6K) than males in the DG (dorsal and ventral) and lower pERK1/2 in the dorsal DG. Most effects of 17β-estradiol on cell signaling occurred in OVX animals. In OVX animals, 17β-estradiol increased cell signaling of MAPK and Akt phosphoproteins (pERK1/2, pJNK, pAkt, and pGSK-3β) in the CA1 and pERK1/2 and pJNK DG.

DISCUSSION/CONCLUSIONS

Systemic 17β-estradiol treatment rapidly alters phosphoprotein levels in the hippocampus, dependent on reproductive status, and intact females have greater expression of Akt phosphoproteins than that in intact males in the DG. These findings shed light on underlying mechanisms of sex differences in hippocampal function and response to interventions that affect MAPK or Akt signaling.

Oestrogen Activates the MAP3K1 Cascade and β-Catenin to Promote Granulosa-like Cell Fate in a Human Testis-Derived Cell Line

Sex determination triggers the differentiation of the bi-potential gonad into either an ovary or testis. In non-mammalian vertebrates, the presence or absence of oestrogen dictates gonad differentiation, while in mammals, this mechanism has been supplanted by the testis-determining gene SRY. Exogenous oestrogen can override this genetic trigger to shift somatic cell fate in the gonad towards ovarian developmental pathways by limiting the bioavailability of the key testis factor SOX9 within somatic cells. Our previous work has implicated the MAPK pathway in mediating the rapid cellular response to oestrogen. We performed proteomic and phosphoproteomic analyses to investigate the precise mechanism through which oestrogen impacts these pathways to activate β-catenin-a factor essential for ovarian development. We show that oestrogen can activate β-catenin within 30 min, concomitant with the cytoplasmic retention of SOX9. This occurs through changes to the MAP3K1 cascade, suggesting this pathway is a mechanism through which oestrogen influences gonad somatic cell fate. We demonstrate that oestrogen can promote the shift from SOX9 pro-testis activity to β-catenin pro-ovary activity through activation of MAP3K1. Our findings define a previously unknown mechanism through which oestrogen can promote a switch in gonad somatic cell fate and provided novel insights into the impacts of exogenous oestrogen exposure on the testis.

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.

In Vitro and In Vivo Evaluation of GSK-3 Radioligands in Alzheimer's Disease: Preliminary Evidence of Sex Differences

Glycogen synthase kinase-3 (GSK-3) is a positron emission tomography (PET) imaging target with implications in the pathogenesis of Alzheimer's disease (AD). This preliminary study evaluates human AD and transgenic P301L mouse brain tissues using the GSK-3-targeting radiotracers [³H]PF-367 and [³H]OCM-44 in radioligand binding assays. A saturation analysis showed decreased GSK-3 density in female human AD compared to a normal healthy brain. Equivalence in density (B _max), affinity (K _d), and apparent affinity (K _i) of both radiotracers was demonstrated to enable their interchangeability for in vitro evaluations of GSK-3 expression. An evaluation of P301L mouse brain by [³H]/[¹¹C]OCM-44 delineated differences in the B _max of GSK-3 between the control and transgenic mice within male subjects. PET imaging showed similar trends to those observed in vitro. Sex differences are revealed as a potential parameter to consider in the development of GSK-3-targeted diagnostics and therapeutics and could guide recruitment for clinical studies.

The Effects of Brain Serotonin Deficiency on Responses to High Fat Diet in Female Mice

Clinical studies have reported an increased risk of depression and anxiety disorders among individuals who are obese, and women are more likely than men to suffer from depression, anxiety, and obesity. However, the effects of obesity-promoting diets on depression- and anxiety-like behavior remain controversial. A recent study from our group used the tryptophan hydroxylase 2 (R439H) knock-in mouse line to evaluate the impact of genetic brain serotonin (5-HT) deficiency on behavioral responses to high fat diet (HFD) in male mice. That study indicated that chronic exposure to HFD induced pro-anxiety-like effects in the open field test and antidepressant-like effects in the forced swim test in wild-type males. Interestingly, the antidepressant-like effect of HFD, but not the anxiogenic effect, was blocked by brain 5-HT deficiency in males. The current work sought to repeat these studies in females. Our new data suggest that females are less susceptible than males to HFD-induced weight gain and HFD-induced alterations in behavior. In addition, the effects of chronic HFD on the expression of inflammation-related genes in the hippocampus were markedly different in females than we had previously reported in males, and HFD was shown to impact the expression of several inflammation-related genes in a genotype-dependent manner. Together, our findings highlight the importance of brain 5-HT and sex in regulating behavioral and molecular responses to HFD. Our results may have important implications for our understanding of the clinically observed sex differences in the consequences of obesity.

Sex differences in fear memory consolidation via Tac2 signaling in mice

Memory formation is key for brain functioning. Uncovering the memory mechanisms is helping us to better understand neural processes in health and disease. Moreover, more specific treatments for fear-related disorders such as posttraumatic stress disorder and phobias may help to decrease their negative impact on mental health. In this line, the Tachykinin 2 (Tac2) pathway in the central amygdala (CeA) has been shown to be sufficient and necessary for the modulation of fear memory consolidation. CeA-Tac2 antagonism and its pharmacogenetic temporal inhibition impair fear memory in male mice. Surprisingly, we demonstrate here the opposite effect of Tac2 blockade on enhancing fear memory consolidation in females. Furthermore, we show that CeA-testosterone in males, CeA-estradiol in females and Akt/GSK3β/β-Catenin signaling both mediate the opposite-sex differential Tac2 pathway regulation of fear memory.

Impairment of the neurotrophic signaling hub B-Raf contributes to motoneuron degeneration in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a motoneuron disease caused by deletions of the Survival of Motoneuron 1 gene (SMN1) and low SMN protein levels. SMN restoration is the concept behind a number of recently approved drugs which result in impressive yet limited effects. Since SMN has already been enhanced in treated patients, complementary SMN-independent approaches are needed. Previously, a number of altered signaling pathways which regulate motoneuron degeneration have been identified as candidate targets. However, signaling pathways form networks, and their connectivity is still unknown in SMA. Here, we used presymptomatic SMA mice to elucidate the network of altered signaling in SMA. The SMA network is structured in two clusters with AKT and 14-3-3 ζ/δ in their centers. Both clusters are connected by B-Raf as a major signaling hub. The direct interaction of B-Raf with 14-3-3 ζ/δ is important for an efficient neurotrophic activation of the MEK/ERK pathway and crucial for motoneuron survival. Further analyses in SMA mice revealed that both proteins were down-regulated in motoneurons and the spinal cord with B-Raf being reduced at presymptomatic stages. Primary fibroblasts and iPSC-derived motoneurons from SMA patients both showed the same pattern of down-regulation. This mechanism is conserved across species since a Caenorhabditis elegans SMA model showed less expression of the B-Raf homolog lin-45 Accordingly, motoneuron survival was rescued by a cell autonomous lin-45 expression in a C. elegans SMA model resulting in improved motor functions. This rescue was effective even after the onset of motoneuron degeneration and mediated by the MEK/ERK pathway.

Impact of Endocrine-Disrupting Chemicals in Breast Milk on Postpartum Depression in Korean Mothers

Previous human and animal studies have reported an association between endocrine-disrupting chemicals (EDCs) and anxiety/depression. This study aimed to determine how the concentrations of phthalate metabolites, bisphenol A, triclosan, and parabens in breast milk are associated with the risk of developing postpartum depression (PPD) in Korean mothers. We recruited 221 mothers who were receiving lactation coaching at breastfeeding clinics between July and September 2018. The breast milk samples were collected along with responses to the Edinburgh Postnatal Depression Scale. The multivariable logistic regression results revealed that the phthalate, bisphenol A, parabens, and triclosan levels in the breast milk were not significantly associated with the risk of PPD. This study was the first attempt to analyze the association between the levels of EDCs in breast milk and the risk of PPD. Considering that PPD is a condition that affects not only the women diagnosed with it, but also their children and families, the results of this study may have great relevance to populations in environmentally sensitive periods.

Exogenous Oestrogen Impacts Cell Fate Decision in the Developing Gonads: A Potential Cause of Declining Human Reproductive Health

The increasing incidence of testicular dysgenesis syndrome-related conditions and overall decline in human fertility has been linked to the prevalence of oestrogenic endocrine disrupting chemicals (EDCs) in the environment. Ectopic activation of oestrogen signalling by EDCs in the gonad can impact testis and ovary function and development. Oestrogen is the critical driver of ovarian differentiation in non-mammalian vertebrates, and in its absence a testis will form. In contrast, oestrogen is not required for mammalian ovarian differentiation, but it is essential for its maintenance, illustrating it is necessary for reinforcing ovarian fate. Interestingly, exposure of the bi-potential gonad to exogenous oestrogen can cause XY sex reversal in marsupials and this is mediated by the cytoplasmic retention of the testis-determining factor SOX9 (sex-determining region Y box transcription factor 9). Oestrogen can similarly suppress SOX9 and activate ovarian genes in both humans and mice, demonstrating it plays an essential role in all mammals in mediating gonad somatic cell fate. Here, we review the molecular control of gonad differentiation and explore the mechanisms through which exogenous oestrogen can influence somatic cell fate to disrupt gonad development and function. Understanding these mechanisms is essential for defining the effects of oestrogenic EDCs on the developing gonads and ultimately their impacts on human reproductive health.

Differential activation of Gsk-3β in the cortex and the hippocampus induces cognitive and behavioural impairments in middle-aged ovariectomized rat

Glycogen synthase kinase-3 (Gsk-3β) aberration act as a crucial pathogenic factor in several neurological conditions. However its role in menopause associated behavioural impairments is still not unclear. The present study was designed to understand the role of Gsk-3β in the progression of neurobehavioural impairments in middle-aged ovariectomized (ovx) rats. The animals showed a significant impairment in spatial and recognition memory, along with anxiety and depression-like behaviour following 22 weeks of ovx. The genomic expression of ERα, ERβ, Nrf2, HO-1, TNFα, and IL-6 was altered in both the cortex and the hippocampus of ovx rats. Protein expression of p-Gsk-3β(Ser9) was significantly downregulated in the cortex after ovx. However, the hippocampus showed a surprisingly opposite trend in the levels of p-Gsk-3β(Ser9) as that of the cortex. Differential activation of Gsk-3β and its downstream proteins such as β-catenin and p-mTOR were also altered following ovx. The study concluded that differential activation of Gsk-3β, along with oxidative stress and neuroinflammation in the cortex and the hippocampus, leads to the induction of cognitive and behaviour impairments in ovx rats.

Effects of letrozole and clomiphene citrate on Wnt signaling pathway in endometrium of polycystic ovarian syndrome and healthy women†

Polycystic ovary syndrome (PCOS) is an endocrine disorder in women of reproductive age. In addition to anovulation, endometrial dysfunction can reduce fertility in PCOS. The cyclical changes of endometrium are controlled by estrogen and progesterone via modulating the Wnt/B-catenin pathway. Clomiphene citrate (CC) and letrozole are used to induce ovulation; unlike letrozole, there is a discrepancy between ovulation and pregnancy rates in CC-treated cycles. Because of the anti-estrogenic effects of CC on endometrium, we compared the expression of the key molecules of the Wnt/B-catenin pathway in the endometrium of women taking CC and letrozole. This study included PCOS and healthy women divided into the groups stimulated with letrozole (5 mg) or CC (100 mg) as well as NO-treatment groups. The endometrial thickness and hormonal profile were measured on day 12 of the menses. Using real-time polymerase chain reaction and western blot, we evaluated mRNA and protein expression of B-catenin, glycogen synthase kinase 3 beta (GSK3B), dickkopf Wnt signaling pathway inhibitor 1 (DKK1), and estrogen receptor 1 (ESR1) in the endometrial samples. Significantly, the mean serum estrogen and progesterone were lower and higher, respectively, in letrozole than CC groups. The endometrial thickness was significantly reduced in CC. The proteins expression of active B-catenin, inactive GSK3B, and ESR1 were significantly decreased in CC-treated groups. The mRNA and protein assessment of DKK1 showed significantly higher expression in CC. Our results indicate that letrozole can provide an acceptable activation of the Wnt/B-catenin pathway, resulting in adequate proliferation of endometrium in the women receiving letrozole compared to CC.

Activation of β-Catenin Signaling and its Crosstalk With Estrogen and Histone Deacetylases in Human Uterine Fibroids

CONTEXT

Uterine fibroids (UF) are the most common benign tumor of the myometrium (MM) in women of reproductive age. However, the mechanism underlying the pathogenesis of UF is largely unknown.

OBJECTIVE

To explore the link between nuclear β-catenin and UF phenotype and β-catenin crosstalk with estrogen and histone deacetylases (HDACs).

DESIGN

Protein/RNA levels of β-catenin (CTNNB1 gene), its responsive markers cyclin D1 and c-Myc, androgen receptor (AR), p27, and class-I HDACs were measured in matched UF/MM tissues or cell populations. The effects of chemical inhibition/activation and genetic knockdown of CTNNB1 on UF phenotype were measured. The anti-UF effect of 2 HDAC inhibitors was evaluated.

MAIN OUTCOME MEASURE

β-catenin nuclear translocation in response to β-catenin inhibition/activation, estrogen, and HDAC inhibitors in UF cells.

RESULTS

UF tissues/cells showed significantly higher expression of nuclear β-catenin, cyclin D1, c-Myc, and HDACs 1, 2, 3, and 8 than MM. Estradiol induced β-catenin nuclear translocation and consequently its responsive genes in both MM and UF cells, while an estrogen receptor antagonist reversed this induction effect. Treatment with β-catenin or HDAC inhibitors led to dose-dependent growth inhibition, while Wnt3a treatment increased proliferation compared with control. Chemical inhibition of β-catenin decreased cyclin D1 and c-Myc expression levels, while β-catenin activation increased expression of the same markers. Genetic knockdown of CTNNB1 resulted in a marked decrease in β-catenin, cyclin D1, c-Myc, and AR expression. Treatment of UF cells with HDAC inhibitors decreased nuclear β-catenin, cyclin D1, and c-Myc expression. Moreover, HDAC inhibitors induced apoptosis of UF cells and cell cycle arrest.

CONCLUSION

β-catenin nuclear translocation contributes to UF phenotype, and β-catenin signaling is modulated by estradiol and HDAC activity.

Glycogen Synthase Kinase 3β in the Ventral Hippocampus is Important for Cocaine Reward and Object Location Memory

The ventral hippocampus is a component of the neural circuitry involved with context-associated memory for reward and generation of appropriate behavioral responses to context. Glycogen synthase kinase 3 beta (GSK3β) has been linked to the maintenance of synaptic plasticity, contextual memory retrieval, and is involved in the reconsolidation of cocaine-associated contextual memory. In this study, the effects of targeted downregulation of GSK3β in the ventral hippocampus were examined on a series of behavioral tests for assessing drug reward-context association and non-reward related memory. The Cre/loxP site-specific recombination system was used to knockdown GSK3β through bilateral stereotaxic delivery of an adeno-associated virus expressing Cre-recombinase (AAV-Cre) into the ventral hippocampus of adult mice homozygous for a floxed GSK3β allele. GSK3β floxed mice injected with AAV-Cre had a loss of 56-75% of GSK3β in the ventral hippocampus and displayed diminished development of cocaine conditioned place preference, but not morphine place preference as compared with wild-type mice injected with AAV-Cre or GSK3β floxed mice injected with a control virus, AAV-GFP. Impaired object location memory was observed in mice with GSK3β downregulation in the ventral hippocampus, but novel object recognition remained intact. These results indicate that GSK3β signaling in the ventral hippocampus is differentially involved in the formation of place-drug reward association dependent upon drug class. Additionally, ventral hippocampal GSK3β signaling is important in detection of discrete spatial cues, but not recognition memory for objects.

Dickkopf-1 blocks 17β-estradiol-enhanced object memory consolidation in ovariectomized female mice

The memory-enhancing effects of 17β-estradiol (E₂) depend upon rapid activation of several cell-signaling cascades within the dorsal hippocampus (DH). Among the many cell-signaling pathways that mediate memory processes, Wnt/β-catenin signaling has emerged as a potential key player because of its importance to hippocampal development and synaptic plasticity. However, whether E₂ interacts with Wnt/β-catenin signaling to promote memory consolidation is unknown. Therefore, the present study examined whether Wnt/β-catenin signaling within the DH is necessary for E₂-induced memory consolidation in ovariectomized mice tested in the object recognition and object placement tasks. Ovariectomized C57BL/6 mice received immediate post-training infusions of E₂ or vehicle into the dorsal third ventricle plus the endogenous Wnt/β-catenin antagonist Dickkopf-1 (Dkk-1) or vehicle into the DH to assess whether the memory-enhancing effects of E₂ depend on activation of Wnt/β-catenin signaling. Our results suggest that Dkk-1 blocks E₂-induced memory enhancement as hypothesized, but may do so by only moderately blunting Wnt/β-catenin signaling while concurrently activating Wnt/JNK signaling. The current study provides novel insights into the mechanisms through which E₂ enhances memory consolidation in the DH, as well as critical information about the mechanistic actions of Dkk-1.

Supraphysiologic-dose anabolic-androgenic steroid use: A risk factor for dementia?

Supraphysiologic-dose anabolic-androgenic steroid (AAS) use is associated with physiologic, cognitive, and brain abnormalities similar to those found in people at risk for developing Alzheimer's Disease and its related dementias (AD/ADRD), which are associated with high brain β-amyloid (Aβ) and hyperphosphorylated tau (tau-P) protein levels. Supraphysiologic-dose AAS induces androgen abnormalities and excess oxidative stress, which have been linked to increased and decreased expression or activity of proteins that synthesize and eliminate, respectively, Aβ and tau-P. Aβ and tau-P accumulation may begin soon after initiating supraphysiologic-dose AAS use, which typically occurs in the early 20s, and their accumulation may be accelerated by other psychoactive substance use, which is common among non-medical AAS users. Accordingly, the widespread use of supraphysiologic-dose AAS may increase the numbers of people who develop dementia. Early diagnosis and correction of sex-steroid level abnormalities and excess oxidative stress could attenuate risk for developing AD/ADRD in supraphysiologic-dose AAS users, in people with other substance use disorders, and in people with low sex-steroid levels or excess oxidative stress associated with aging.

Estrogen-mediated protection against coronary heart disease: The role of the Notch pathway

Estrogen regulates a plethora of biological processes, under physiological and pathological conditions, by affecting key pathways involved in the regulation of cell proliferation, fate, survival and metabolism. The Notch receptors are mediators of communication between adjacent cells and are key determinants of cell fate during development and in postnatal life. Crosstalk between estrogen and the Notch pathway intervenes in many processes underlying the development and maintenance of the cardiovascular system. The identification of molecular mechanisms underlying the interaction between these types of endocrine and juxtacrine signaling are leading to a deeper understanding of physiological conditions regulated by these steroid hormones and, potentially, to novel therapeutic approaches to prevent pathologies linked to reduced levels of estrogen, such as coronary heart disease, and cardiotoxicity caused by hormone therapy for estrogen-receptor-positive breast cancer.

Neuroprotective Strategies for Neurological Disorders by Natural Products: An update

Nature has bestowed mankind with surplus resources (natural products) on land and water. Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. These natural products have been experimentally documented to possess various biological properties such as antioxidant, anti-inflammatory and anti-apoptotic activities. In vitro and in vivo studies have further established the usefulness of natural products in various preclinical models of neurodegenerative disorders. Natural products include phytoconstituents, like polyphenolic antioxidants, found in herbs, fruits, nuts, vegetables and also in marine and freshwater flora. These phytoconstituents may potentially suppress neurodegeneration and improve memory as well as cognitive functions of the brain. Also, they are known to play a pivotal role in the prevention and cure of different neurodegenerative diseases, such as Alzheimer's disease, epilepsy, Parkinson's disease and other neuronal disorders. The large-scale neuro-pharmacological activities of natural products have been documented due to the result of either the inhibition of inflammatory processes, or the up-regulation of various cell survival proteins or a combination of both. Due to the scarcity of human studies on neuroprotective effects of natural products, this review focuses on the various established activities of natural products in in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications using the available knowledge in the literature.

Neuroprotection and improvement of the histopathological and behavioral impairments in a murine Alzheimer's model treated with Zephyranthes carinata alkaloids

In Alzheimer's disease (AD), amyloid beta (Aβ) plaques initiates a cascade of pathological events where the overactivation of N-methyl-d-aspartate receptors (NMDA) by excess glutamate (Glu) triggers oxidative processes that lead to the activation of microglial cells, inflammation, and finally neuronal death. Amaryllidaceae alkaloids exert neuroprotective activities against different neurotoxin-induced injuries in vitro, and although their biological potential is well demonstrated, their neuroprotective activity has not been reported in an in vivo model of AD. The aim of our study was to determine the in vitro and in vivo neuroprotective potential of standardized alkaloidal fractions of Zephyranthes carinata. In this work, the neuroprotective effect of two alkaloidal fractions extracted from Z. carinata (bulbs and leaves) was analyzed in an in vitro excitotoxicity model in order to select the most promising one for subsequent evaluation in a triple transgenic mouse model of AD (3xTg-AD). We found that Z. carinata bulbs protect neurons against a Glu-mediated toxic stimulus in vitro, as evidenced by the decrease in apoptotic nuclei, the reduction in the lipid peroxidation product malondialdehyde and the conservation of dendritic structures. The effects of intraperitoneal administration of Z. carinata bulbs (10 mg/kg) every 12 h for 1 month on 3xTg-AD (18 months old) showed improved learning and spatial memory. Histopathologically, the alkaloidal fraction-treated 3xTg-AD mice exhibited a significant reduction in tauopathy and astrogliosis, as well as a significant decrease in the proinflammatory marker COX-2 and an increase in pAkt. The results suggest that Z. carinata bulbs provide neuroprotective effects both in vitro and in 3xTg-AD mice by intervening in the inflammatory processes, regulating the aggregation of pair helical filaments (PHFs) and activating survival pathways.

The effects of letrozole and clomiphene citrate on ligands expression of Wnt3, Wnt7a, and Wnt8b in proliferative endometrium of women with Polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrinologic disorder in women of reproductive age characterized by polycystic ovaries, oligo/anovulation, and hyperandrogenism. Not only anovulation but also endometrial dysfunction can reduce fertility in PCOS patients. Wnt pathway is responsible for endometrial proliferation which be strongly regulated by estradiol. To determine the effects of clomiphene citrate (CC) and letrozole, we measured the expression of some main ligands of Wnt/β-catenin signaling including Wnt7a, Wnt3, and Wnt8b in the endometrial samples taken from PCOS women on day 12 of the menses who received 100 mg CC or 5 mg letrozole as well as from women without treatment. Significantly, the mean estrogen and progesterone concentration were lower and higher, respectively, in letrozole than CC. The mean endometrial thickness (ET) was significantly greater in letrozole compared to CC. Assessment of the mRNA and protein expression of Wnt7a, Wnt3, and Wnt8b showed significantly lower expression in CC than the letrozole and control groups. Collectively, letrozole provided a better molecular response in the endometrium of PCOS patients during the proliferative phase, similar to natural cycles, compared to CC. CC decreased the ligands expression of Wnt3, Wnt7a, and Wnt8b, resulting in endometrial dysfunction.

Human umbilical cord blood mesenchymal stem cells engineered to overexpress growth factors accelerate outcomes in hair growth

Human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) are used in tissue repair and regeneration; however, the mechanisms involved are not well understood. We investigated the hair growth-promoting effects of hUCB-MSCs treatment to determine whether hUCB-MSCs enhance the promotion of hair growth. Furthermore, we attempted to identify the factors responsible for hair growth. The effects of hUCB-MSCs on hair growth were investigated in vivo, and hUCB-MSCs advanced anagen onset and hair follicle neogeneration. We found that hUCB-MSCs co-culture increased the viability and up-regulated hair induction-related proteins of human dermal papilla cells (hDPCs) in vitro. A growth factor antibody array revealed that secretory factors from hUCB-MSCs are related to hair growth. Insulin-like growth factor binding protein-1 (IGFBP-1) and vascular endothelial growth factor (VEGF) were increased in co-culture medium. Finally, we found that IGFBP-1, through the co-localization of an IGF-1 and IGFBP-1, had positive effects on cell viability; VEGF secretion; expression of alkaline phosphatase (ALP), CD133, and β-catenin; and formation of hDPCs 3D spheroids. Taken together, these data suggest that hUCB-MSCs promote hair growth via a paracrine mechanism.

WWOX Phosphorylation, Signaling, and Role in Neurodegeneration

Homozygous null mutation of tumor suppressor WWOX/Wwox gene leads to severe neural diseases, metabolic disorders and early death in the newborns of humans, mice and rats. WWOX is frequently downregulated in the hippocampi of patients with Alzheimer’s disease (AD). In vitro analysis revealed that knockdown of WWOX protein in neuroblastoma cells results in aggregation of TRAPPC6AΔ, TIAF1, amyloid β, and Tau in a sequential manner. Indeed, TRAPPC6AΔ and TIAF1, but not tau and amyloid β, aggregates are present in the brains of healthy mid-aged individuals. It is reasonable to assume that very slow activation of a protein aggregation cascade starts sequentially with TRAPPC6AΔ and TIAF1 aggregation at mid-ages, then caspase activation and APP de-phosphorylation and degradation, and final accumulation of amyloid β and Tau aggregates in the brains at greater than 70 years old. WWOX binds Tau-hyperphosphorylating enzymes (e.g., GSK-3β) and blocks their functions, thereby supporting neuronal survival and differentiation. As a neuronal protective hormone, 17β-estradiol (E2) binds WWOX at an NSYK motif in the C-terminal SDR (short-chain alcohol dehydrogenase/reductase) domain. In this review, we discuss how WWOX and E2 block protein aggregation during neurodegeneration, and how a 31-amino-acid zinc finger-like Zfra peptide restores memory loss in mice.

Sex steroid hormones as neuroprotective elements in ischemia models

Among sex steroid hormones, progesterone and estradiol have a wide diversity of physiological activities that target the nervous system. Not only are they carried by the blood stream, but also they are locally synthesized in the brain and for this reason, estradiol and progesterone are considered 'neurosteroids'. The physiological actions of both hormones range from brain development and neurotransmission to aging, illustrating the importance of a deep understanding of their mechanisms of action. In this review, we summarize key roles that estradiol and progesterone play in the brain. As numerous reports have confirmed a substantial neuroprotective role for estradiol in models of neurodegenerative disease, we focus this review on traumatic brain injury and stroke models. We describe updated data from receptor and signaling events triggered by both hormones, with an emphasis on the mechanisms that have been reported as 'rapid' or 'cytoplasmic actions'. Data showing the therapeutic effects of the hormones, used alone or in combination, are also summarized, with a focus on rodent models of middle cerebral artery occlusion (MCAO). Finally, we draw attention to evidence that neuroprotection by both hormones might be due to a combination of 'cytoplasmic' and 'nuclear' signaling.

Pir2/Rnf144b is a potential endometrial cancer biomarker that promotes cell proliferation

Endometrial cancer is one of the most common gynaecological cancers in developed countries. Its incidence has increased 20% over the last decade and the death rate has increased >100% over the past two decades. Current models for prediction of prognosis and treatment response are suboptimal, and as such biomarkers to support clinical decision-making and contribute to individualised treatment are needed. In this study, we show that the E3-ubiquitin ligase PIR2/RNF144B is a potential targetable biomarker in endometrial cancer. At transcript level, it is expressed both in normal endometrium and tumour samples, but at protein level, it is expressed in tumours only. By using endometrial cancer cell lines, we demonstrated that PIR2/RNF144B is stabilised via phosphorylation downstream of GSK3β and this is necessary for the proliferation of endometrial cancer cells, in the absence of oestrogenic growth stimuli. Here, inactivation of GSK3β activity is associated with loss of PIR2/RNF144B protein and consequent inhibition of cell proliferation. Our results, therefore, substantiate PIR2/RNF144B as a novel candidate for targeted therapy in endometrial cancer.

Estradiol Activates PI3K/Akt/GSK3 Pathway Under Chronic Neurodegenerative Conditions Triggered by Perinatal Asphyxia

Perinatal asphyxia (PA) remains as one of the most important causes of short-term mortality, psychiatric and neurological disorders in children, without an effective treatment. In previous studies we have observed that the expression of different neurodegenerative markers increases in CA1 hippocampal area of 4-months-old male rats born by cesarean section and exposed for 19 min to PA. We have also shown that a late treatment with 17β estradiol (daily dose of 250 μg/kg for 3 days) was able to revert the brain alterations observed in those animals. Based on these previous results, the main aim of the present study was to explore the mechanism by which the estrogenic treatment is involved in the reversion of the chronic neurodegenerative conditions induced by PA. We demonstrated that estradiol treatment of adult PA exposed animals induced an increase in estrogen receptor (ER) α and insulin-like growth factor receptor (IGF-1R) protein levels, an activation of the phosphatidylinositol 3-kinase/Akt/glycogen synthase kinase 3 beta/β-catenin signaling pathway and an increase in Bcl-2/Bax ratio in the hippocampus in comparison to PA exposed animals treated with vehicle. Taking together, our data suggest that the interaction between ERα and IGF-IR, with the subsequent downstream activation, underlies the beneficial effects of estradiol observed in late treatment of PA.

Role of mTORC1 Controlling Proteostasis after Brain Ischemia

Intense efforts are being undertaken to understand the pathophysiological mechanisms triggered after brain ischemia and to develop effective pharmacological treatments. However, the underlying molecular mechanisms are complex and not completely understood. One of the main problems is the fact that the ischemic damage is time-dependent and ranges from negligible to massive, involving different cell types such as neurons, astrocytes, microglia, endothelial cells, and some blood-derived cells (neutrophils, lymphocytes, etc.). Thus, approaching such a complicated cellular response generates a more complex combination of molecular mechanisms, in which cell death, cellular damage, stress and repair are intermixed. For this reason, animal and cellular model systems are needed in order to dissect and clarify which molecular mechanisms have to be promoted and/or blocked. Brain ischemia may be analyzed from two different perspectives: that of oxygen deprivation (hypoxic damage per se) and that of deprivation of glucose/serum factors. For investigations of ischemic stroke, middle cerebral artery occlusion (MCAO) is the preferred in vivo model, and uses two different approaches: transient (tMCAO), where reperfusion is permitted; or permanent (pMCAO). As a complement to this model, many laboratories expose different primary cortical neuron or neuronal cell lines to oxygen-glucose deprivation (OGD). This ex vivo model permits the analysis of the impact of hypoxic damage and the specific response of different cell types implicated in vivo, such as neurons, glia or endothelial cells. Using in vivo and neuronal OGD models, it was recently established that mTORC1 (mammalian Target of Rapamycin Complex-1), a protein complex downstream of PI3K-Akt pathway, is one of the players deregulated after ischemia and OGD. In addition, neuroprotective intervention either by estradiol or by specific AT2R agonists shows an important regulatory role for the mTORC1 activity, for instance regulating vascular endothelial growth factor (VEGF) levels. This evidence highlights the importance of understanding the role of mTORC1 in neuronal death/survival processes, as it could be a potential therapeutic target. This review summarizes the state-of-the-art of the complex kinase mTORC1 focusing in upstream and downstream pathways, their role in central nervous system and their relationship with autophagy, apoptosis and neuroprotection/neurodegeneration after ischemia/hypoxia.

Tau Phosphorylation in Female Neurodegeneration: Role of Estrogens, Progesterone, and Prolactin

Sex differences are important to consider when studying different psychiatric, neurodevelopmental, and neurodegenerative disorders, including Alzheimer's disease (AD). These disorders can be affected by dimorphic changes in the central nervous system and be influenced by sex-specific hormones and neuroactive steroids. In fact, AD is more prevalent in women than in men. One of the main characteristics of AD is the formation of neurofibrillary tangles, composed of the phosphoprotein Tau, and neuronal loss in specific brain regions. The scope of this work is to review the existing evidence on how a set of hormones (estrogen, progesterone, and prolactin) affect tau phosphorylation in the brain of females under both physiological and pathological conditions.

The regulation of Hh/Gli1 signaling cascade involves Gsk3β- mediated mechanism in estrogen-derived endometrial hyperplasia

The present study was undertaken to explore the functional involvement of Hh signaling and its regulatory mechanism in endometrial hyperplasia. Differential expression of Hh signaling molecules i.e., Ihh, Shh, Gli1 or Gsk3β was observed in endometrial hyperplasial (EH) cells as compared to normal endometrial cells. Estradiol induced the expression of Hh signaling molecules and attenuated the expression of Gsk3β whereas anti-estrogen (K1) or progestin (MPA) suppressed these effects in EH cells. Cyclopamine treatment or Gli1 siRNA knockdown suppressed the growth of EH cells and reduced the expression of proliferative markers. Estradiol also induced the nuclear translocation of Gli1 which was suppressed by both MPA and K1 in EH cells. While exploring non-canonical mechanism, LY-294002 (Gsk3β activator) caused a decrease in Gli1 expression indicating the involvement of Gsk3β in Gli1 regulation. Further, Gsk3β silencing promoted the expression and nuclear translocation of Gli1 demonstrating that Gsk3β serves as a negative kinase regulator of Gli1 in EH cells. Similar attenuation of Hh signaling molecules was observed in rats with uterine hyperplasia undergoing anti-estrogen treatment. The study suggested that Hh/Gli1 cascade (canonical pathway) as well as Gsk3β-Gli1 crosstalk (non-canonical pathway) play crucial role in estrogen-dependent cell proliferation in endometrial hyperplasia.

Role of glycogen synthase kinase 3 in ischemia-induced blood-brain barrier disruption in aged female rats

Estrogen receptors have protective effects against ischemic brain injury. However, the molecular mechanisms underlying this phenomenon have yet to be well studied. Given that inhibition of glycogen synthase kinase (GSK3) can reduce cerebral ischemia/reperfusion injury, we hypothesized that estrogen receptors-mediated protective effects against ischemia-induced blood-brain barrier (BBB) disruption involve inhibition of GSK3. Thus, we evaluated GSK3 expression in the brain of ovariectomized female rats, and examined the effects of intracerebroventricular pre-treatments of SB216763, GSK3 inhibitor, on BBB permeability following middle cerebral artery occlusion (MCAO). We also examined the role of specific estrogen receptor subtype in regulation of GSK3 expression and BBB permeability after MCAO. We found that ovariectomized female rats exhibited increased mRNA levels of estrogen receptor α (ERα) and estrogen receptor β (ERβ), and increased protein levels of GSK3β but not GSK3α in brain cortical areas. Furthermore, intracerebroventricular pre-treatments of SB216763 dose-dependently attenuated brain infarction volume, brain water contents, neurological deficits, and BBB disruption, and increased tight junction protein ZO-1 and occludin expression at 24 h following MCAO. Finally, activation of ERβ but not ERα dose-dependently decreased GSK3β expression at 24 h following MCAO. This was associated with increased tight junction protein expression and improved neurological scores. Thus, our study suggested that activation of ERβ may protect against brain ischemia-induced BBB disruption by inhibiting GSK3β-mediated signaling.

Pathophysiology of Aortic Valve Stenosis: Is It Both Fibrocalcific and Sex Specific?

Our understanding of the fundamental biology and identification of efficacious therapeutic targets in aortic valve stenosis has lagged far behind the fields of atherosclerosis and heart failure. In this review, we highlight the most clinically relevant problems facing men and women with fibrocalcific aortic valve stenosis, discuss the fundamental biology underlying valve calcification and fibrosis, and identify key molecular points of intersection with sex hormone signaling.

Integrating insulin-like growth factor 1 and sex hormones into neuroprotection: Implications for diabetes

Brain integrity and cognitive aptitude are often impaired in patients with diabetes mellitus, presumably a result of the metabolic complications inherent to the disease. However, an increasing body of evidence has demonstrated the central role of insulin-like growth factor 1 (IGF1) and its relation to sex hormones in many neuroprotective processes. Both male and female patients with diabetes display abnormal IGF1 and sex-hormone levels but the comparison of these fluctuations is seldom a topic of interest. It is interesting to note that both IGF1 and sex hormones have the ability to regulate phosphoinositide 3-kinase-Akt and mitogen-activated protein kinases-extracellular signal-related kinase signaling cascades in animal and cell culture models of neuroprotection. Additionally, there is considerable evidence demonstrating the neuroprotective coupling of IGF1 and estrogen. Androgens have also been implicated in many neuroprotective processes that operate on similar signaling cascades as the estrogen-IGF1 relation. Yet, androgens have not been directly linked to the brain IGF1 system and neuroprotection. Despite the sex-specific variations in brain integrity and hormone levels observed in diabetic patients, the IGF1-sex hormone relation in neuroprotection has yet to be fully substantiated in experimental models of diabetes. Taken together, there is a clear need for the comprehensive analysis of sex differences on brain integrity of diabetic patients and the relationship between IGF1 and sex hormones that may influence brain-health outcomes. As such, this review will briefly outline the basic relation of diabetes and IGF1 and its role in neuroprotection. We will also consider the findings on sex hormones and diabetes as a basis for separately analyzing males and females to identify possible hormone-induced brain abnormalities. Finally, we will introduce the neuroprotective interplay of IGF1 and estrogen and how androgen-derived neuroprotection operates through similar signaling cascades. Future research on both neuroprotection and diabetes should include androgens into the interplay of IGF1 and sex hormones.

Estrogen and ERα enhanced β-catenin degradation and suppressed its downstream target genes to block the metastatic function of HA22T hepatocellular carcinoma cells via modulating GSK-3β and β-TrCP expression

In our previous experiments, we found β-catenin was highly expressed in the tumor area with high invasive ability and poor prognosis. In this study, we have examined the mechanism by which ERα regulates β-catenin expression as well as the metastasis ability of hepatocellular cancer HA22T cells. To identify whether the anticancer effect of estrogen and ERα is mediated through suppression of β-catenin expression, we co-transfected pCMV-β-catenin and ERα into HA22T cells, and determined the cell motility by wound healing, invasion, and migration assays. Results showed that estrogen and/or ERα inhibited β-catenin gene expression and repressed HA22T cell motility demonstrated that similar data was observed in cells expressing the ERα stable clone. Moreover, we examined the protein-protein interaction between ERα and β-catenin by immunostain, co-immunoprecipitation, and Western blotting. E2 enhanced the binding of ERα with β-catenin and then triggered β-catenin to bind with E3 ligase (βTrCP) to promote β-catenin degradation. Finally by employing systematic ChIP studies, we showed ERα can interact directly with the β-catenin promoter region following E2 treatment. All our results reveal that estrogen and ERα blocked metastatic function of HA22T cells by modulating GSK3β and βTrCP expression and further enhanced β-catenin degradation and suppressed its downstream target genes. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 519-529, 2017.

CCAAT/enhancer binding protein β negatively regulates progesterone receptor expression in human glioblastoma cells

Many progesterone (P4) actions are mediated by its intracellular receptor (PR), which has two isoforms (PR-A and PR-B) differentially transcribed from separate promoters of a single gene. In glioblastomas, the most frequent and aggressive brain tumors, PR-B is the predominant isoform. In an in silico analysis we showed putative CCAAT/Enhancer Binding Protein (C/EBP) binding sites at PR-B promoter. We evaluated the role of C/EBPβ in PR-B expression regulation in glioblastoma cell lines, which expressed different ratios of PR and C/EBPβ isoforms (LAP1, LAP2, and LIP). ChIP assays showed a significant basal binding of C/EBPβ, specific protein 1 (Sp1) and estrogen receptor alpha (ERα) to PR-B promoter. C/EBPβ knockdown increased PR-B expression and treatment with estradiol (E2) reduced C/EBPβ binding to the promoter and up-regulated PR-B expression. P4 induced genes were differently regulated when CEBP/β was silenced. These data show that C/EBPβ negatively regulates PR-B expression in glioblastoma cells.

Multimodal Imaging of Neurometabolic Pathology due to Traumatic Brain Injury

The impact of traumatic brain injury (TBI) involves a combination of complex biochemical processes beginning with the initial insult and lasting for days, months and even years post-trauma. These changes range from neuronal integrity losses to neurotransmitter imbalance and metabolite dysregulation, leading to the release of pro- or anti-apoptotic factors which mediate cell survival or death. Such dynamic processes affecting the brain's neurochemistry can be monitored using a variety of neuroimaging techniques, whose combined use can be particularly useful for understanding patient-specific clinical trajectories. Here, we describe how TBI changes the metabolism of essential neurochemical compounds, summarize how neuroimaging approaches facilitate the study of such alterations, and highlight promising ways in which neuroimaging can be used to investigate post-TBI changes in neurometabolism.

The C/EBPδ protein is stabilized by estrogen receptor α activity, inhibits SNAI2 expression and associates with good prognosis in breast cancer

Hypoxia and inflammatory cytokines like interleukin-6 (IL-6, IL6) are strongly linked to cancer progression, and signal in part through the transcription factor Ccaat/enhancer-binding protein δ (C/EBPδ, CEBPD), which has been shown to promote mesenchymal features and malignant progression of glioblastoma. Here we report a different role for C/EBPδ in breast cancer. We found that the C/EBPδ protein is expressed in normal breast epithelial cells and in low-grade cancers. C/EBPδ protein (but not mRNA) expression correlates with estrogen receptor (ER+) and progesterone receptor (PGR) expression and longer progression-free survival of breast cancer patients. Specifically in ER+ breast cancers, CEBPD-but not the related CEBPB-mRNA in combination with IL6 correlated with lower risk of progression. Functional studies in cell lines showed that ERα promotes C/EBPδ expression at the level of protein stability by inhibition of the FBXW7 pathway. Furthermore, we found that C/EBPδ attenuates cell growth, motility and invasiveness by inhibiting expression of the SNAI2 (Slug) transcriptional repressor, which leads to expression of the cyclin-dependent kinase inhibitor CDKN1A (p21CIP1/WAF1). These findings identify a molecular mechanism by which ERα signaling reduces the aggressiveness of cancer cells, and demonstrate that C/EBPδ can have different functions in different types of cancer. Furthermore, our results support a potentially beneficial role for the IL-6 pathway specifically in ER+ breast cancer and call for further evaluation of the role of intra-tumoral IL-6 expression and of which cancers might benefit from current attempts to target the IL-6 pathway as a therapeutic strategy.

BACE1 RNAi Restores the Composition of Phosphatidylethanolamine-Derivates Related to Memory Improvement in Aged 3xTg-AD Mice

β-amyloid (Aβ) is produced by the β-secretase 1 (BACE1)-mediated enzymatic cleavage of the amyloid precursor protein through the amyloidogenic pathway, making BACE1 a therapeutic target against Alzheimer’s disease (AD). Alterations in lipid metabolism are a risk factor for AD by an unknown mechanism. The objective of this study was to determine the effect of RNA interference against BACE1 (shBACEmiR) on the phospholipid profile in hippocampal CA1 area in aged 3xTg-AD mice after 6 and 12 months of treatment compared to aged PS1KI mice. The shBACEmiR treatment induced cognitive function recovery and restored mainly the fatty acid composition of lysophosphatidylethanolamine and etherphosphatidylethanolamine, reduced the cPLA2’s phosphorylation, down-regulated the levels of arachidonic acid and COX2 in the hippocampi of 3xTg-AD mice. Together, our findings suggest, for the first time, that BACE1 silencing restores phospholipids composition which could favor the recovery of cellular homeostasis and cognitive function in the hippocampus of triple transgenic AD mice.

The WNT-less wonder: WNT-independent β-catenin signaling

β-catenin is known as an Armadillo protein that regulates gene expression following WNT pathway activation. However, WNT-independent pathways also activate β-catenin. During the establishment of the melanocyte lineage, β-catenin plays an important role. In the context of physiopathology, β-catenin is activated genetically or transiently in various cancers, including melanoma, where it can be found in the nucleus of tumors. In this review, we discuss alternative pathways that activate β-catenin independent of WNTs and highlight what is known regarding these pathways in melanoma. We also discuss the role of β-catenin as a transcriptional regulator in various cell types, with emphasis on the different transcription factors it associates with independent of WNT induction. Finally, the role of WNT-independent β-catenin in melanocyte development and melanomagenesis is also discussed.

p120-catenin is necessary for neuroprotection induced by CDK5 silencing in models of Alzheimer's disease

Cyclin-dependent kinase 5 (CDK5) plays important roles in synaptic function. Its unregulated over-activation has been, however, associated with neurodegeneration in Alzheimer's disease. Our previous studies revealed that CDK5 silencing ameliorates tauopathy and spatial memory impairment in the 3xTgAD mouse model. However, how CDK5 targeting affects synaptic adhesion proteins, such as those involved in the cadherin/catenin system, during learning and memory processes is not completely understood. In this study, we detected reduced expression of p120 catenin (p120 ctn), N-cadherin, and β-catenin in the brain of human Alzheimer's disease patients, in addition to a reduced PSD95 and GluN2B protein levels in a 3xTgAD mouse model. Such decrease in synaptic proteins was recovered by CDK5 silencing in mice leading to a better learning and memory performance. Additionally, CDK5 inhibition or knockout increased p120 ctn levels. Moreover, in a glutamate-induced excitotoxicity model, CDK5 silencing-induced neuroprotection depended on p120 ctn. Together, those findings suggest that p120 ctn plays an important role in the neuronal dysfunction of Alzheimer's disease models and contributes to CDK5 silencing-induced neuroprotection and improvement of memory function. p120ctn is part of the synaptic adhesion molecular complex N-cadh/p120ctn/B-ctn/PSD95, and it has a pivotal role in cell adhesion stabilization and dendritic spine modulation. Our data show that synaptic adhesion complex is affected in AD human brains and in AD models. This complex is recovered by the silencing of CDK5, preventing memory dysfunction in an AD mice model and contributing to the neuroprotection in a depend-mode of p120ctn.

Reproductive Steroid Regulation of Mood and Behavior

In this article, we examine evidence supporting the role of reproductive steroids in the regulation of mood and behavior in women and the nature of that role. In the first half of the article, we review evidence for the following: (i) the reproductive system is designed to regulate behavior; (ii) from the subcellular to cellular to circuit to behavior, reproductive steroids are powerful neuroregulators; (iii) affective disorders are disorders of behavioral state; and (iv) reproductive steroids affect virtually every system implicated in the pathophysiology of depression. In the second half of the article, we discuss the diagnosis of the three reproductive endocrine-related mood disorders (premenstrual dysphoric disorder, postpartum depression, and perimenopausal depression) and present evidence supporting the relevance of reproductive steroids to these conditions. Existing evidence suggests that changes in reproductive steroid levels during specific reproductive states (i.e., the premenstrual phase of the menstrual cycle, pregnancy, parturition, and the menopause transition) trigger affective dysregulation in susceptible women, thus suggesting the etiopathogenic relevance of these hormonal changes in reproductive mood disorders. Understanding the source of individual susceptibility is critical to both preventing the onset of illness and developing novel, individualized treatments for reproductive-related affective dysregulation. © 2016 American Physiological Society. Compr Physiol 6:1135-1160, 2016e.

Hippocampal Wnt Signaling: Memory Regulation and Hormone Interactions

Wnt signaling has emerged in recent years as a major player in both nervous system development and adult synaptic plasticity. Of particular relevance to researchers studying learning and memory, Wnt signaling is critical for normal functioning of the hippocampus, a brain region that is essential for many types of memory formation and whose dysfunction is implicated in numerous neurodegenerative and psychiatric conditions. Impaired hippocampal Wnt signaling is implicated in several of these conditions, however, little is known about how Wnt signaling mediates hippocampal memory formation. This review will provide a general overview of Wnt signaling and discuss evidence demonstrating a key role for Wnt signaling in hippocampal memory formation in both normal and disease states. The regulation of Wnt signaling by ovarian sex steroid hormones will also be highlighted, given that the neuroprotection afforded by Wnt-hormone interactions may have significant implications for cognitive function in aging, neurodegenerative disease, and ischemic injury.